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GUTOT'S    GEOGRAPHICAL    SERIES. 


Physical 


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GEOGRAPHY 


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BY 


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ARNOLD    GUYOT, 


of  "Earth  and  Man. 


( 


NEW   YORK: 

Charles  Scribner's  Sons, 


19 


X 


m- 


* 


Sntared  according  to  Act  of  Congress,  in  the  year  1S73,  by 

SORIBNER,    ARMSTRONG,    &    CO., 

In  the  Office  of  the  Librarian  ot  Congress,  at  Washington. 


£jue*kib« 


RIVERSIDE,     CAMBRIDGE . 

SLECTROTYPED    AND    PRINTED    BI 

H.  O.   HOUGHTON  AND  COMPANY. 

Kuan: 

GIFT 


§.  a  ess 

I  ?73 


PREFACE. 




t-tst^oC  , 


Physical  Geogeaphy,  in  the  highest  sense  of  the  term,  is  the  Science  of  the  Earth  as  a  great  individual  organization.  In  this 
science  the  material  body  of  the  globe,  wi^h  its  atmosphere,  the  myriads  of  plants  and  animal  forms  living  upon  it,  and  man  himself,  as  a 
part  of  the  life-system,  are  not  only  considered  in  themselves  but  in  their  mutual  relations,  as  working  together  towards  a  common  end. 
Though  entirely  resting  upon  the  solid  basis  of  observed  phenomena,  it  does  not  stop  there.  Its  aim  is  preeminently  the  discovery  of  the 
laws  which  govern  these  phenomena,  and  of  the  grand  chain  of  causes  and  effects  which  explains  the  mode  of  their  occurrence. 

Such  a  study  requires  an  extensive  knowledge  of  facts  drawn  from  the  domain  of  all  the  natural  and  physical  sciences,  which  cannot 
be  expected  of  the  youthful  student,  and  a  habit  of  generalization  which  does  not  belong  to  the  early  stages  of  mental  development.  A 
full  treatment  of  Physical  Geography  and  its  intricate  problems  is,  therefore,  more  in  place  in  the  highest  institutions  of  learning  than  in 
our  general  school  system. 

But  by  far  the  greater  number  of  the  youth  in  our  schools  will  never  enter  the  walls  of  a  college  or  university.  A  glance,  however, 
at  the  subjects  treated  in  the  present  work,  will  convince  every  thoughtful  mind  that,  in  this  age  of  universal  education,  it  woidd  be  a 
grievous  mistake  to  send  this  multitude  into  the  wide  world  of  active  life,  without  some  knowledge  of  the  laws  of  these  natural  phenom- 
ena, in  the  midst  of  which  we  live  and  move. 

The  mariner  on  the  stormy  sea,  the  agriculturist  at  home,  the  merchant  embracing  the  world  in  his  commercial  ventures,  the  far-see- 
ing statesman  —  all  have  a  direct  interest  in  knowing  the  course  of.  the  winds,  the  laws  of  the  distribution  of  heat  and  rains,  which  regu- 
late the  abundance  or  scarcity  of  crops,  determine  the  special  nature  of  the  useful  productions  in  every  part  of  the  inhabitable  globe,  and, 
in  consequence,  the  resources  and  the  intercourse  of  the  civilized  nations. 

The  problem  to  be  solved  in  preparing  the  work  was  to  furnish  to  the  pupils  of  higher  grades  a  general  outline  of  Physical  Geog- 
raphy which,  by  its  simplicity  and  conciseness,  would  be  suited  both  to  the  amount  of  general  information  they  are  expected  to  possess, 
and  tho  limited  time  available  for  this  study  in  the  school  course.  This  task  the  author  has  attempted  to  perform  without  sacrificing  the 
special  character  of  the  science.  All  parts  of  the  subject  are  presented  in  their  true  relations,  as  the  writer  conceives  them,  and  in  their 
proper  subordination.  They  form  a  body  of  facts  strongly  connected  together  by  ties  of  mutual  dependence,  which,  once  well  understood 
and  thoroughly  mastered,  in  the  spirit  of  the  book,  cannot  fail  to  be  easily  and  forever  remembered,  while,  at  the  same  time,  they  estab- 
lish a  sound  basis  for  future  progress. 

In  every  part  of  the  work  a  strict  geographical  point  of  view  has  been  preserved.  From  the  kindred  sciences  —  geology,  natural 
philosophy,  meteorology  —  only  such  facts  and  principles  have  been  borrowed  as  were  necessary  to  illustrate  geographical  phenomena.  In 
the  exposition  of  the  life-system  the  associations  of  plants,  animals,  aud  races  of  men  in  geographical  groups,  characterizing  the  great 
natural  divisions  of  the  globe,  have  been  defined,  and  not  the  botanical,  zoological,  or  ethnological  classifications. 

To  enliven  the  presentation  of  the  subject  by  vivid  descriptions  of  remarkable  phenomena,  or  countries,  would  have  been  a  pleasant 
and  easy  task,  but  the  prescribed  space  forbade  any  such  indulgence.  A  text-book  can  be  but  little  more  than  a  skeleton  designed  to  give 
solidity,  and  to  put  order  and  method  in  the  structure  to  be  erected.  To  the  intelligent  teacher  belongs  the  privilege  of  clothing  these 
dry  bones  with  forms  of  life  and  beauty.  But  the  teacher  and  the  pupil  will  find  an  invaluable  help  in  the  analyses  placed  at  the  end  of 
the  sections,  and  it  is  hoped  that  the  latter  will  be  thus  induced  to  perform  that  mental  process  without  which  a  real  acquisition  of  knowl- 
edge is  simply  impossible. 

The  numerous  maps  constitute  in  themselves  a  work  as  laborious  as  it  is  indispensable.  They  have  been  prepared  with  great  care, 
and  are  thought  to  embody  the  results  obtained  to  the  present  day  in  this  domain  of  scientific  inquiry.  The  illustrations  have  been 
selected  strictly  with  a  view  to  instruct  the  pupil,  and  not  simply  to  adorn  the  pages  of  the  volume  ;  and  the  execution  of  the  work  gives 
ample  evidence  that  the  publishers  have  spared  neither  pains  nor  expense  to  do  justice  to  the  subject  and  extend  the  usefulness  of  this 
manual. 

This  volume  closes  the  series,  now  complete,  of  the  geographical  text-books  which  the  author  had  engaged  to  prepare  for  our  public 
schools.  It  represents  the  highest  of  the  three  normal  stages  of  study,  alluded  to  and  fully  defined  hi  the  preface  of  the  lower  books,  and 
in  the  accompanying  manual  of  geographical  teaching.  Experience  has  shown  that,  in.  the  hands  of  the  proper  teacher,  —  and  we  ought 
not  to  have  any  others,  —  these  manuals  carry  the  pupil  to  the  aim  with  ease,  and  by  gradual  and  sure  steps.  It  is  a  most  gratifying  fact 
that  the  method  on  which  they  are  based  has  received  the  full  indorsement  of  the  best  educators  both  in  this  country  and  abroad. 

To  those  who,  having  used  the  first  books  of  this  series,  have  patiently  waited  for  this  work,  the  author  begs  to  express  his  sincere 
regret  that  an  unexpected  interruption  in  his  usual  health,  which  rendered  a  prolonged  absence  necessary,  should  have  retarded,  for  more 
than  two  years,  the  issue  of  this  volume. 

With  this  last  offering  the  author  takes  leave  of  the  youth  of  our  schools,  and  their  teachers,  with  an  already  well-grounded  assur- 
ance that  more  than  a  half  score  of  his  best  years,  earnestly  devoted  to  the  introduction  of  a  method  of  instruction  more  rational  than 
that  of  mechanical  memorizing,  —  which  is  still  the  bane  o'f  too  many  of  our  schools,  and  the  strongest  barrier  to  all  progress,  —  have 
not  been  spent  in  vain  for  the  cause  of  public  education. 

Whether  a  manual  of  a  higher  kind,  for  the  mature  student  and  the  scientific  public  at  large,  can  be  prepared,  remains  in  the  hands 
of  Providence  rather  than  in  the  writer's  will  and  desires.  ^  ARNOLD   GUYOT 

Pkinceton,  New  Jeksev,  b^U  BMr  Professor  0f  Physical  Geography  ami 

April  25,  1873.  Geology,  College  of  New  Jersey. 


-.-■■! 


ANALYSIS    OF   THE   VOLUME. 


PART  J.  — THE    EARTH. 

I.  Introduction.    Nature  of  Physical  Geography.     Subdivisions. 
II.  The  Earth  in  the  Universe. 

III.  The  Earth  in  the  Solar  System. 

IV.  The  Globe,  —  its  Form,  Volume,  and  Mass. 

V.  The  Globe,  —  its  Circles  and  Surface  Measurements. 
VI.  The  Globe  as  a  Magnet. 

VII.  Temperature  of  the  Globe,  independently  of  the  Sun's  Rays. 
VIII.  Results  of  Internal  Heat.     Volcanic  Phenomena. 
IX.  Results  Continued.    Distribution  and  Cause  of  Volcanoes. 
X.  Results  Continued.    Earthquakes. 
XI.  Review  of  Part  I. 


PART   II.  — THE   LAND. 

I.  General  Arrangement  of  the  Land  Masses. 
II.  Horizontal  Forms  of  the  Continents. 

III.  Relief  Forms  classified.     Plains  Described. 

IV.  Reliefs  Continued.    Plateaus.    Mountains.     Valleys. 
V.  Structure  of  the  New  World  Described. 

VI.  Structure  of  Asia. 
VII.  Structure  of  Europe. 
VIII.  Structure  of  Africa  and  Australia. 
IX.  General  Laws  of  Continental  Reliefs. 

X.  Islands  classified.    Formation  of  Coral  and  Volcanic  Islands. 
XI.  Review  of  Pasts  I.  and  II. 


PART   III.  — THE    WATERS. 

I.  Water  as  a  Geographical  Element. 
II.  Continental  Waters. 

1.  Rivers,  —  their  Formation  and  their  Agency. 

2.  Lakes, —  their  Formation  and  Distribution. 

3.  Drainage  of  North  America  described. 

4.  Drainage  of  South  America. 

5.  Drainage  of  Asia  and  Europe. 

6.  Drainage  of  Africa  and  Australia. 
HI.  The  Sea. 

1.  Introduction.     Composition  of  Water.     Temperature. 

Bottom. 

2.  The  Oceans.     Their  Forms,  Sizes,  Depths,  etc. 

3.  Oceanic  Movements.     Waves  and  Tides. 

4.  Marine  Currents. 
IV.  Review  of  Part  HI. 


Marine  Life.     Sea 


PART   IV.  — THE    ATMOSPHERE. 

I.  The  Atmosphere  as  a  Geographical  Element.     Climate. 
II.  Astronomical  Climate.    Law  of  Distribution  of  Heat.    Influence  of 

Earth's  Motion. 
HL  Physical  Climate.    Deviations  from  Astronomical  Climate,  Classifi- 
cation and  Cause. 
IV.  The  Winds.    General  Circulation  of  Atmosphere.     Trade  Winds. 
V.  Winds  Continued.    Periodical  Winds.    Variable  Winds. 
VI.  Revolving  Storms.    Character  and  Cause. 
VIL  Distribution  of  Vapor  in  the  Atmosphere. 
VIII.  Time  and  Character  of  Rains  in  Different  Latitudes. 
IX.  Rainfall  of  the  Different  Continents. 
X.  Snow,  Horizontal  and  Vertical  Distribution. 
XI.  Glaciers,  Formation  and  Geographical  Distribution. 
XII.  Optical  and  Luminous  Phenomena  of  the  Atmosphere. 
XIII.  Review  of  Part  IV. 


PART  V— LIFE    UPON  THE   EARTH. 

1.  Life  in  Nature. 

1.  Introduction. 

2.  Vegetation  in  the  Different  Latitudes. 

3.  Distribution  of  Vegetation  in  the  Northern  Continents. 

4.  Vertical  Distribution  of  Vegetation. 

5.  Vegetation  of  the  Southern  Continents. 

6.  Aspects  of  Nature  in  Different  Zones. 

7.  Animals  of  the  three  Northern  Continents. 

8.  Animals  of  the  Southern  Continents. 

H.  Provision  for  Human  Life  and  Social  Progress. 

1-  Materials  for  Sustenance,  Raiment,  and  Shelter. 

2.  Minerals  Employed  in  the  Arts. 
HI.  The  Human  Family. 

1.  The  Geographical  Races,  their  Locations  and  Characteristics. 

2.  Law  of  Variation  of  Types. 

3.  Historical  Importance  of  the  several  Races. 
IV.  Conclusion. 

1.  The  great  Terrestrial  Contrasts. 

a.  Continental  and  Oceanic  Worlds 

b.  Eastern  and  Western  Worlds. 

c.  Northern  and  Southern  Worlds. 

2.  The  Continents  of  History. 

a.  Historical  Function  of  Asia. 

b.  Historical  Function  of  Europe. 

c.  Historical  Function  of  North  America. 

V.  Reviews,  etc. 

1.  Review  of  Part  V. 

2.  General  Review. 

3.  Vocabulary. 

4.  Tables  of  Mean  Temperature  and  Rainfall. 


1.  The  Solar  System 

2.  Lines  of  Equal  Magnetic  Declination 

3.  Distribution  of  Volcanoes  and  Earthquakes 


Page 
4 
.      9 
18 


4.  Physical  Map  of  the  World  (Mercator) •      .  28 

5.  Structure  of  North  America  (Diagram) 31 

6.  Structure  of  South  America  (Diagram) 32 

7.  Structure  of  Asia  (Diagram) 34 

8.  Structure  of  Europe  (Diagram) 36 

9.  Structure  of  Central  Europe  (Diagram) 37 

10.  Structure  of  Africa  (Diagram) 38 

11.  Structure  of  Australia  (Diagram) 39 

12.  Tide  Waves  and  River  Basins  of  the  Globe 63 


LIST  OF  MAPS. 

Page 

13.  Tidal  Wave  of  the  British  Isles 64 

14.  Marine  Currents 66 

15.  Isothermal  Lines 74 

16.  Winds 80 

17.  Rains 86 

18.  Distribution  of  Vegetation  on  the  Globe 98 

19.  Vertical  Distribution  of  Vegetation 102 

20.  Aspects  of  Nature  in  Different  Latitudes 1°6 

21.  Distribution  of  Useful  Minerals  and  Precious  Metals         .  113 

22.  The  Races  of  Men 117 

23.  The  United  States.    River  Basins •  120 

24.  The  United  States.     Vegetation 12° 


PHYSICAL   GEOGRAPHY. 

PART   I. 
'     THE    EARTH. 


ALEXANDER  VON  HUMBOLDT. 
(From  the  portrait  by  Schroder,  in  possession  of  Albert  Bavemeyer,  Esq.,  New  York.) 

I.  — NATURE   OF  PHYSICAL  GEOGRAPHY. 


I.  Subject  of  Geographical  Science. 

Thb  Eabth,  as  an  individual  organization  with  a  definite  struc- 
ture, character,  and  purpose,  is  the  subject  of  geographical  science. 
The  globe  as  a  whole,  the  three  great  geographical  elements  which 
it  comprises,  —  the  land,  the  water,  and  the  atmosphere,  —  and  the 
organic  life  which  it  supports,  each  presents  peculiar  classes  of  phe- 
nomena which  it  is  the  province  of  the  scientific  geographer  to 
investigate,  both  in  their  individual  character  and  their  mutual  rela- 
tions. 


- 


II.  Points  of  View  in  which  the  Earth  may  be  studied. 

The  Eartti,  as  the  subject  of  geographical  science,  may  be  re- 
garded in  two  different  points  of  view  :  — 

1.  In  itself,  as  a  master-piece  of  Divine  workmanship,  perfect  in 
all  its  parts  and  conditions. 

2.  In  its  PURPOSE,  as  the  abode  of  Man,  the  scene  of  his  activity, 
and  the  means  of  his  development. 

The  first  gives  rise  to  the  Geography  of  Nature,  the  second  to  the 
Geography  of  Man. 


THE  EARTH  IN   THE   UNIVERSE. 


III.  Geography  of  Nature. 

The  MODE  OF  treatment  in  the  geography  of  nature  may  be 
either  simply  descriptive,  or  scientific. 

1.  Descriptive  natural  geography,  or  Physiography,1  is  a 
simple  description  of  the  surface  of  the  globe  —  of  the  position,  ex- 
tent and  character  of  the  lands ;  the  distribution  and  extent  of  the 
waters ;  and  the  nature  of  the  climate  and  productions  in  different 
parts  of  the  Earth.     It  forms  the  basis  of  scientific  geography. 

2.  Scientific  natural  geography,  or  Physical  Geography 
proper,  not  only  describes  the  various  phenomena  exhibited  by  the 
Earth  as  an  individual  organization,  but  seeks  to  discover  the  laws 
which  govern  them,  and  investigates  their  relations,  causes  and 
consequences.  This  department  of  geography  is  frequently,  and 
very  properly,  called  Terrestrial  Physics.2 

IV.  Problems  of  Physical  Geography. 

Among  the  problems  which  physical  geography  aims  to  solve  are 
the  following :  — 

1.  What  laws  govern  the  situation,  extent,  outlines,  and  relief  3  of 
the  land  masses  ? 

2.  What  is  the  influence  of  the  relief  of  the  continents  upon  the 
formation  of  their  systems  of  rivers  and  lakes  ? 

3.  What  is  the  cause,  the  extent,  the  connection,  and  the  influence 
of  the  great  oceanic  currents  ? 

4.  What  is  the  fundamental  law  of  the  distribution  of  heat  upon 
the  surface  of  the  globe  ;  what  modifications  of  this  law  are  observ- 
able ;  and  how  are  those  modifications  produced  ? 

5.  What  general  atmospheric  movements  have  been  observed,  and 
what  is  their  cause,  course  and  influence  ? 

6.  What  laws  control  the  periods,  distribution,  and  amount  of  rain 
upon  different  portions  of  the  globe ;  and  how  is  the  existence  of 
vast  rainless  regions  in  certain  latitudes  to  be  accounted  for  ? 

7.  What  general  laws  govern  the  distribution  of  vegetable  and 
animal  life  upon  the  globe,  and  how  are  these  laws  related  to  the 
character  and  well-being  of  the  human  family  ? 

V.  Results  of  a  Study  of  Physical  Geography. 

A  careful  study  of  physical  geography  tends  to  lead  the  mind  to 
the  conclusion  that  the  great  geographical  constituents  of  our  planet 
—  the  solid  land,  the  ocean,  and  the  atmosphere  - —  are  mutually  de- 
pendent and  connected  by  incessant  action  and  reaction  upon  one 
another  ;  and  hence,  that  the  Earth  is  really  a  wonderful  mechan- 
ism, all  parts  of  which  work  together  harmoniously  to  accomplish 
the  purpose  assigned  to  it  by  an  All-wise  Creator. 

VI.  Physical  Geography  distinguished  from  Geology. 

1.  Geology,  sometimes  wrongly  included  in  physical  geography, 
is  the  study  of  the  Earth  under  quite  another  aspect.  It  describes, 
in  their  succession,  the  past  ages  of  the  globe,  before  the  creation  of 
man,  and  seeks  to  give  a  true  history  of  the  long  periods  of  gradual 
formation  by  which  it  was  made  ready  for  the  reception  of  mankind. 

Like  all  other  bodies  in  nature,  the  Earth  had  its  periods  of  slow,  gradual  forma- 
tion, preceding  its  completed  state.  The  rocks  composing  the  solid  mass  of  the 
land  were  long  ages  in  forming  ;  the  continents  emerged  by  slow  successive  steps 
from  beneath  the  sea,  system  after  system  of  mountains  contributing  to  their  final 

1  From  two  Greek  words,  phusis,  nature,  and  grapho,  to  write. 

2  From  the  Greek  phutikos,  pertaining  to  nature.     Terrestrial,  belonging  to  the  Earth. 

3  Elevatien  of  the  surface. 


figu.-e  and  relief ;  tribes  of  animals  and  plants,  differing  from  existing  species,  ap- 
peared successively  in  vast  numbers,  during  untold  periods  of  time.  These  suc- 
cessive stages  of  progress  form  the  materials  for  the  science  of  geology. 

2.  Physical  Geography,  on  the  contrary,  concerns  itself  only 
with  the  present  completed  condition  of  the  globe  ;  thus  it  begins 
where  geology  ends.     Its  natural  subdivisions  are  as  follows :  — 

1.  The  Earth  as  a  whole. 

2.  The  Land. 

3.  The  Water. 

4.  The  Atmosphere. 

5.  The  Life  upon  the  globe. 

ANALYSIS  OF   SECTION  I. 
I.  Subject  of  Geographical  Science. 

II.  Points  of  View  in  Geographical  Study. 

1    Earth  considered  in  itself. 

2.  Earth  considered  in  its  purpose. 

3.  Results. 

III.  Geography  of  Nature. 

1 .  Modes  of  treatment  distinguished. 

2.  Physiography. 

a.  Definition. 

b.  Derivation  of  name. 

c.  Relation  to  higher  study. 

3.  Physical  Geography. 

a.  Definition. 

b.  Other  name,  derivation  of. 

IT.  Problems  Investigated  by  Physical  Geography. 

1.  Relief,  etc.,  op  Land  Masses. 
2-  Influence  of  Relief  on  Drainage. 

3.  Ocean  Currents. 

4.  Distribution  of  Heat. 

5.  Atmospheric  Currents. 

6.  Laws  of  Rain-fall. 

7-  Distribution  of  Life  on  Globe. 

V.  Results  of  Geographical  Study. 

1.  Geographical  Constituents  connected  and  mutually  depf,xdent. 

2.  The  Earth  a  Mechanism  designed  for  a  Definite  Purpose. 

VI.  Distinction  between  Geology  and  Physical  Geography. 

1.  Geology  studies  Past  Conditions 

2.  Physical  Geography  studies  Present  Conditions. 
8   Subdivision  of  Physical  Geographt. 


II.  — THE  EARTH  IN  THE  UNIVERSE. 

I.  The  Universe. 

The  Universe  is  a  general  term  used  to  represent  the  entire  ma- 
terial creation.  Our  knowledge  of  it,  however,  is  confined  to  a  par- 
tial acquaintance  with  the  Earth  and  its  sister  planets ;  and  some 
general  ideas  in  regard  to  the  more  distant  heavenly  bodies,  whose 
existence  is  revealed  to  us  only  by  the  light  they  shed  upon  the 
Earth. 

II.  The  Starry  Heavens. 

1.  The  Heavenly  Bodies,  which  occupy  the  immensity  of 
space,  appear  to  be  arranged  in  groups,  or  systems,  sweeping 
through  immeasurable  circuits. 

Our  Sun  is  the  self-luminous  centre  of  a  group  of  small  non-lumi- 
nous bodies  called  Planets,*  which  reflect  his  light,  and  revolving 
around  him  accompany  him  through  space.  Our  Earth  is  one  of 
these  planets.  These  solid  bodies,  together  with  a  few  apparently 
gaseous  and  partially  self-luminous  bodies  called  Comets,  form  the 
Solar  System. 

The  fixed  stars,  which  adorn  the  heavens  in  countless  numbers, 
are  suns  —  many  of  them  of  vastly  greater  magnitude  than  our  Sun 

- —  some  revolving  around  one  another,  while  others,  possibly,  are 

— — — 1 

4  Planet,  from  the  Greek  planao,  to  wander. 


THE  EARTH  IN  THE  SOLAR  SYSTEM. 


the  centres  of  planetary  systems  like  ours.  They  are  at  such  vast 
distances  from  us  that  their  light  alone  is  within  the  reach  of  our 
observation. 

2.  The  Magnitude  of  the  Starry  Heaven  is  such  that  our 
entire  solar  system,  extending  over  an  area  5,550  millions  of  miles  in 
diameter,  is  only  a  point  in  the  boundless  space. 

A  ray  of  light  from  the  Sun,  travelling  185,600  miles  in  a  second 
of  time,  reaches  Neptune,  the  most  distant  known  planet,  in  a  little 
more  than  four  hours ;  but  it  requires  more  than  three  years  to  reach 
the  nearest  fixed  star,  and  three  years  more  to  reach  the  next.  It  may 
travel  on,  from  system  to  system,  for  two  or  three  thousand  years 
before  reaching  the  limits  of  the  starry  heavens  visible  to  the  naked 
Bye. 


III.  IVebulie. 

Separated  from  our  starry  heavens  by  empty  abysses  of  inconceiv- 
able magnitude,  are  other  heavenly  bodies  called  nebula?,  of  which 
more  than  6,000  have  been  observed. 

Some  of  these,  seen  through  the  most  powerful  telescopes  yet  pro- 
duced, appear  only  as  small  shining  clouds,  whence  their  name.1 
Others  have  been  found  to  be  composed  of  multitudes  of  stars, 
apparently  clustered  together,  but,  doubtless,  as  widely  separated  as 
tlie  stars  above  us.  Thus  there  may  be  other  starry  heavens,  pos- 
sibly yet  more  extensive  than  that  which  gladdens  our  eyes. 


IV.  Insignificance  of  the  Earth. 

Tin;  Earth,  therefore,  vast  as  it  seems  to  the  feeble  mind  of  man, 
is  only  one  of  the  smaller  members  of  a  little  family  of  planets.  The 
Sun,  the  all-controlling  centre  of  this  family,  with  a  multitude  of 
other  suns,  forms  one  group  of  stars  in  the  immensity  of  the  visible 
heavens  ;  while  the  measureless  firmament  itself  is  filled  with 
myriads  of  star  clusters,  which  "declare  the  glory  oi  God"  and 
••  show  forth  his  handiwork." 


ANALYSIS  OF  SECTION  H. 

I.  The  Universe. 

1.  Significance  of  tf.rm. 

2.  Extent  of  our  knowledge  of  it. 

II.  The  Starry  Heavens. 

1.  Heavenly  Bodies  grouped. 

(Sun. 
a.  Solar  System,  -i  Planets. 

|  COHietS. 

!  Character. 
Distance. 

2.  Magnitude  of  Starry  Heavens. 

a.  Exteut  of  Solar  System. 

b.  Distance  of  nearest  fixed  stars. 

c.  Distance  of  bounds  of  visible  stars 


b.    Fixed  Stars.  • 


III.  Nebulae. 

1.  Their  Position. 

2.  Their  Number. 

3.  Their  Appearance. 

4.  Their  Probable  Character. 

IV.  Comparative  Insignincauce  of  the  Earth. 

1.  The  Earth  in  Solar  System. 

2.  Solar  System  in  Srv  Si 

3.  Sun  Groups  in  Visible  Hi.  , 

4.  Star  Clusters  in  Firm  i 


III.  —  THE  EARTH  IN  THE  SOLAR  SYSTEM. 

I.  Bodies  Composing  the  Solar  System. 

The  Solar  System  consists  of  the  Sun  —  the  central  and  controlling 
body  —  eight  primary  planets,  and  twenty  secondary  planets  or  satel- 
lites revolving  around  their  several  primaries  ;  more  than  one  hun- 
dred and  twenty  asteroids,2  which  are  small  planets  visible  only 
through  the  telescope ;  and  an  indefinite  number  of  comets. 

The  primary  planets  are  separated  by  the  asteroids  into  two 
groups  of  four  each,  one  between  the  asteroids  and  the  Sun,  the 
other  beyond  them.  Recent  observations  render  probable  the  ex- 
istence of  another  planet  between  the  Sun  and  Mercury. 

II.  Primary  Planets. 

1.  Relative  Position.  The  primary  planets,  in  the  order  of 
their  position,  are  Mercury,  —  the  nearest  to  the  Sun,  — Venus,  the 
Earth,  and  Mars,  composing  the  first  group  ;  Jupiter,  Saturn,  Uranus, 
and  Neptune,  composing  the  second. 

2.  Comparative  Size.  The  size  of  the  planets,  in  general,  in- 
creases with  their  distance  from  the  Sun.  The  four  composing  the 
first  group  are  all  comparatively  small,  the  Earth  being  the  largest. 
Those  of  the  second  group  are  all  of  great  size.  Jupiter,  the 
largest,  is  not  less  than  1,390  times  as  large  as  the  Earth ;  but  as  it 
is  much  less  dense,  the  amount  of  matter  it  contains  is  only  a  trifle 
more  than  337  times  that  of  the  Earth.  All  the  planets  together 
equal  but  7-Jjj  part  of  the  mass  of  the  Sun. 

3.  Comparative  Density.  The  density  of  the  planets  decreases 
with  their  distance  from  the  Sun.  Mercury,  the  most  dense,  has  a 
specific  gravity3  of  8^,  a  little  greater  than  that  of  iron  ;  the  Earth, 
of,  and  Venus  and  Mars  about  the  same  ;  Jupiter,  lj ;  and  Saturn, 
the  least  dense  of  all  the  planets,  but  §,  or  about  the  same  as  cork. 

4.  The  Distance  bet w  ken  the  Primary  Planets  increases 
with  their  increasing  distance  from  the  Sun.  Reckoning  the  asteroids 
as  one  place,  and  excepting  Neptune,  the  distances  of  the  successive 
orbits  from  the  orbit  of  Mercury  increase  in  very  nearly  a  twofold 
ratio.  Thus  from  Mercury  to  Venus  is  31  millions  of  miles;  to  the 
Earth,  56  millions  ;  to  Mars,  105  millions,  etc. 

The  four  smaller  planets  are  all  comparatively  near  the  Sun,  their 
several  distances  from  it  being  only  36,  67,  92,  and  141  millions  of 
miles ;  Avhile  Jupiter,  the  nearest  of  the  great  planets,  is  481  millions 
of  miles  distant. 

5.  The  Satellites,  except  our  Moon,  belong  wholly  to  the 
second  group  of  planets.  Jupiter  has  four ;  Saturn  eight,  and  sev- 
eral revolving  rings  ;  Uranus  has  four,  and  possibly  more ;  while 
Neptune,  so  far  as  known  with  certainty,  has  but  one. 

III.  Movements  Within  the  Solar  System. 

1.  Rotary  Motion.  The  Sun,  all  the  primary  planets,  and  their 
satellites,  as  far  as  known,  rotate  from  west  to  east.  Each 
rotation  constitutes  a  day  for  the  rotating  body.  The  central  line 
of  rotary  motion  is  called  the  axis  of  rotation,  and  the  extremities  of 
the  axis  are  called  the  Poles. 

2.  Revolution  around  the  Sun.  All  the  primary  planets 
and  asteroids  revolve  around  the  Sun  in  the  direction  of  their  rota- 
tion, that  is  from  west  to  east ;  and  the  planes 4  of  the  orbits  in  which 


1  From  the  Latin  nebula,  a  little  cloud. 


-  These  may  be  fragments  of  a  former  great  planet  occupying  the  same  place  ill  the  sysMn. 

8  Weight  as  compared  with  an  equal  bulk  of  pure  water. 

4  The  ideal  plane  in  which  their  circular  path  is  conceived  to  lie. 


^fc  SOLAR    BTstxjit 


i*r 


T*E  ABOVE    DlAG^AlJt 
THE    RELATIVE    SIZES  OP"  THE  SUN  &  PLANETS    ARE   PRESERVED 

THE    SIZE     OF    THE    SUN    BEING  BEPBESENTED     BY    THE     OBBIT    OF     NEPTUNE  . 


flt       *~«Nr  •»*        Asteroids 


JupiU-r 


Saturn 


Uranus 


t     %  ^  >»,    7*        *30 


881  1.772 

COMPARATIVE    DISTANCES    OF  THE  PLANETS   FROM  THE  SUN 


Neptune 


HSmnlox  P.)  hlti  hi  noli  iter 


THE  EARTH  IN  THE  SOLAR  SYSTEM. 


they  revolve  coincide  very  nearly  with  the  plane  of  the  Sun's  equator.1 
One  revolution  around  the  Sun  constitutes  the  year  of  a  planet. 

All  the  satellites  except  those  of  Uranus  and  perhaps  Neptune, 
also  revolve  from  west  to  east. 

Most  of  the  comets  revolve  around  the  Sun  in  very  irregular  and  elongated 
orbits,  only  a  few  having  their  entire  orbit  within  the  planetary  system.  Some  so 
move  that  after  having  entered  our  system  and  made  their  circuit  around  the  Sun, 
they  seem  to  leave  it  never  to  return. 

3.  Velocity  op  Planetary  Movements.  The  velocity  of  the 
planets  in  their  annual  revolutions  decreases  as  their  distance  from 
the  Sun  increases.  Mercury  moves  at  the  rate  of  nearly  2£  millions 
of  miles  per  day,  and  the  Earth  1|  millions ;  while  Neptune  advances 
at  the  slower  pace  of  little  more  than  £  of  a  million. 

The  velocity  of  rotation,  on  the  contrary,  is  least  in  the  smaller 
planets  which  are  near  the  Sun,  while  it  is  greatest  in  the  larger 
and  more  distant  ones.  The  former  require  from  23£  to  24^  hours 
of  our  time  for  one  rotation ;  while  the  latter,  except  Neptune, 
whose  rotary  velocity  is  not  known,  accomplish  an  entire  rotation  in 
from  9^  to  10|  hours. 

4.  Time  of  Revo- 
lution. As  the  or- 
bits of  the  planets  in- 
crease in  circumference 
with  their  distance  from 
the  Sun,  and  their  ve- 
locity at  the  same  time 
diminishes,  the  time  of 
revolution,  or  length  of 
the  year,  increases  cor- 
respondingly. Mercury 
performs  a  revolution  in 
about  88  days  of  our 
time ;  and  the  Earth,  in 
365£ ;  while  Jupiter  re- 
quires 4,332,  and  Nep- 
tune 60,126  days. 

5.  The  axes  of  all 
the  planets,  so  far  as 
known,  are  more  or  less 
inclined  towards  the 
planes   of   their   orbits. 

This  inclination  causes  an  apparent  passing  of  the  Sun  from  one 
hemisphere  to  the  other  during  the  course  of  the  annual  revolution, 
thereby  producing  variation  in  the  relative  length  of  day  and  night, 
and  change  of  seasons.  The  greater  the  inclination  of  the  axis,  the 
greater  is  the  variation  in  the  length  of  day  and  night,  and  the  more 
extreme  the  contrasts  in  temperature  during  the  year  at  any  given 
point. 

The  Earth  seems  to  present  a  happy  medium  in  this  respect.  Its 
axis  is  inclined  about  23£° ,2  sufficient  to  give  the  larger  part  of  its 
surface  four  seasons  of  nearly  equal  length  —  Summer,  Winter,  and 
two  transition  seasons  of  medium  temperature  —  with  day  and  night 
varying  from  9  or  10  to  14  or  15  hours ;  while  but  a  small  area,  ex- 
tending 23^  degrees  from  each  pole,  is  ever  entirely  deprived  of  the 
Sun's  rays  during  one  or  more  rotations  of  the  Earth.  The  two 
polar  regions  combined  occupy  but  16£  millions  of  square  miles,  out 
of  197  millions,  the  entire  surface  of  the  Earth. 

If  the  axis  of  the  planet  Venus  be,  as  is  supposed,  inclined   72°,  then  in  the 


course  of  its  annual  revolution  the  Sun  must  be  vertical  on  every  part  of  its 
surface  except  a  little  area  extending  15°  from  the  poles,  where  it  is  so  nearly 
vertical  as  to  produce  scarcely  less  heat  than  if  it  were  so.  Thus  every  part  of  its 
surface  must  alternate  between  excessive  heat  during  one  half  the  year,  and  in- 
tense cold,  from  an  almost  entire  absence  of  the  Sun's  rays,  durin<*  the  other  half. 

6.  Eccentricity  of  Planetary  Orbits.  The  planetary 
orbits  are  not  exact  circles,  but  are  more  or  less  elliptical,  the  Sun 
being  situated  not  at  the  centre,  but  at  one  of  the  foci  of  the  ellipse. 
The  distance  of  either  focus  from  the  centre  is  called  the  eccentricity 
of  the  ellipse.  On  account  of  this  eccentricity  the  distance  of  a 
planet  from  the  Sun,  and  its  velocity  of  revolution,  vary  in  different 
parts  of  its  orbit. 

Some  of  the  planets  are  so  much  nearer  the  Sun  in  one  portion 
of  their  orbit  than  in  another,  that  the  degree  of  heat  received  varies 
greatly  in  different  seasons  of  the  year.  Thus  Mercury  receives, 
when  nearest  the  Sun,  about  2j  times  as  much  heat  as  when  most 
distant  from  it,  a  difference  equal  to  the  variation  in  temperature 
between  summer  and  winter  in  the  middle  latitudes  of  our  globe. 

The  Earth,  on  the 
contrary,  revolves  in  an 
orbit  but  slightly  eccen- 
tric. Its  nearest  ap- 
proach to  the  Sun  oc- 
curs in  the  winter  of  the 
northern  hemisphere, 
where  the  larger  part  of 
the  land  is  concentrated. 
Hence,  if  this  slight  ec- 
centricity of  the  orbit 
has  any  appreciable  ef- 
fect upon  climate,  it 
must  be  to  moderate  the 
cold  of  winter,  and  the 
heat  of  summer,  in  the 
most  populous  .zone  of 
the  globe. 


THE    ORBIT    OF    THE    EARTH. 


IV.  Advantages  in  Con- 
ditions of  the  Earth. 


1  A  great  circle  the  plane  of  which  cuts  the  axis  of  rotation  at  right  angles. 
1  In  more  exact  terms,  23°  27'. 


The  Earth  is  thus 
subject  to  physical  conditions  intermediate  between  the  extremes 
presented  by  the  other  planets. 

It  is  the  largest  of  the  smaller  planets,  and  occupies  a  middle 
position  in  the  group.  This  frees  it  alike  from  the  blinding  glare  and 
burning  heat  to  which  Mercury  is  exposed,  and  the  dimness  of  light 
and  the  cold  which  must  prevail  on  distant  Jupiter  and  Neptune. 

The  comparative  velocities  of  its  diurnal  and  annual  motions,  the 
trifling  eccentricity  of  its  orbit,  and  the  slight  inclination  of  its  axis, 
establish  a  harmony  in  the  relative  length  of  its  days,  years,  and 
seasons,  and  its  alternations  of  temperature  and  of  light  and  dark- 
ness, such  as  cannot  exist  in  most  of  the  other  planets. 

Thus  the  Earth  appears  better  fitted  than  any  other  member  of  the 
solar  system  for  sustaining  that  great  wealth  of  organic  life  —  vege- 
table, animal,  and  human  —  with  which  it  is  endowed,  and  which 
constitutes  its  greatest  glory.  Indeed,  whatever  may  have  been  the 
the  past,  or  may  be  the  future  of  the  other  planets,  it  is  doubtful 
whether,  at  the  present  time,  any  one  of  them  possesses  those  physi- 
cal conditions  under  which  alone  a  life-system  at  all  similar  to  ours 
is  possible. 


THE   TERRESTRIAL   GLOBE. 


.-> 


ANALYSIS   OF   SECTION  HI. 

I.  Bodies  Composing  the  Solar  System. 

1.  Sun,  its  Bank. 

2.  Primary-  Planets,  their  Number. 

3.  Satellites,  Number  and  Relation  to  Primaries. 

4.  Asteroids,  Number  and  Size. 
6.  Comets. 
6.  Grouping  op  Planets. 

II.  Primary  Planets. 

1.  Relative  Position. 

2.  Comparative  Size. 

a.  Law  of  increase. 

b.  Size  of  first  group. 

c.  Size  of  second  group. 
(1.  Total  mass  compared  with  Sun. 

3.  Comparative  Density. 

a.  Law  of  decrease. 

b.  Specific  gravity  of  small  planets. 

c.  Specific  gravity  of  Jupiter  and  Saturn. 

4.  Planetary  Distances. 

a.  Law  of  increase. 

b.  Distance  of  small  planets  from  Sun. 

c.  Distance  of  great  planets  from  Sun. 
6.  Satellites. 

a.  To  which  group  belonging. 

b.  Number  accompanying  each  great  planet. 

III.  Movements  within  Solar  System. 

1.  Rotary  Motion. 

a.  Direction. 

b.  Resulting  measure  of  time. 

c.  Centre. 

2.  Revolution  around  the  Sun. 

(  Primary  planets. 

a.  Direction  of  motion.  \  Asteroids. 

[  Satellites. 

b.  Measure  of  time. 

c.  Revolution  of  comets. 

3.  Velocities  of  Planetary  Motions. 

a.  Law  of  variation  in  revolution.     Examples. 

b.  Law  of  variation  in  rotation.    Examples. 

4.  Time  op  Revolution. 

a.  Law  of  variation.    Example. 
6.  Axis  op  Rotation. 

a.  Law  of  position. 

b.  General  effect  of  inclination. 

o.  Earth,  degree  of  Inclination.    Results. 

d.  Venus.    Supposed  degree  of  inclination.    Results. 
6.  Eccentricity  of  Orbits.    Definition. 

a.  Mercury,  Comparative  Eccentricity.    Results. 

b.  Earth,  Comparative  Eccentricity.    Results. 

IV.  Advantages  In  Physical  Condition  of  Earth. 

1.  Of  Position  in  Solar  System. 

2.  Of  Velocity  op  Motions,  Eccentricity  op  Orbit,  and  Inclination  op  Axis. 


IV.  — THE   TERRESTRIAL  CxLOBE. 


ITS  FORM  ;   VOLUME  ;  MASS. 

I.  Form  of  the  Earth. 

1.  The  Earth,  as  ascertained  by  mathematical  measurements,  is 
an  oblate  spheroid,  being  slightly  compressed  about  the  poles,  and 
slightly  bulging  in  the  equatorial  regions.  The  difference  between 
the  polar  and  the  equatorial  radius  is  only  13£  miles. 

2.  This  deviation  from  a  perfectly  spherical  figure  is  such  as  would  be  pro- 
duced by  the  rotation  of  a  slightly  plastic  1  globe  upon  its  axis.  It  indicates  that  the 
Earth,  in  some  period  of  its  existence,  must  have  been  in  a  semi-fluid  condition. 


II.  Volume  or  Bulk  of  the  Terrestrial  Globe. 

1.  The  term  volume,  as  applied  to  the  Earth,  signifies  its  size 
or  dimensions,  as  shown  by  measurements,  irrespective  of  the  amount 
of  matter  contained  in  it. 


1  Capable  of  being  moulded  or  shaped. 


2.  The  dimensions  of  the  Earth  according  to  Herschel  are :  — 

Equatorial  diameter 7,925.65  miles. 

Polar  »  7,899.17      " 

Mean  "  7,916  " 

Circumference  at  equator        .     .     .  24,899  " 

Extent  of  surface      ....    196,900,278      square  miles. 
Solid  contents      ....  260,000,000,000      cubic  miles. 

3.  The  APPROXIMATE  DIMENSIONS,  expressed  in  round  numbers 
for  convenience  in  remembering  them,  are  —  diameter,  8,000  miles  ; 
circumference,  25,000  miles ;  extent  of  surface,  197  millions  of  square 
miles ;  solid  contents,  260  thousand  millions  of  cubic  miles. 

« 
III.  Mass  of  the  Globe. 

1.  The  term  mass,  as  applied  to  the  Earth,  signifies  the  amount 
of  matter  it  contains  irrespective  of  its  volume. 

Material  substances  differ  greatly  in  the  mass  of  matter  contained  in  a  given 
volume.  Thus  a  cubic  foot  of  stone  weighs  2£  times  as  much  as  a  cubic  foot  of 
water,  that  is,  contains  2£  times  as  much  matter ;  in  other  words,  its  specific  grav- 
ity is  2J.     The  specific  gravity  of  iron  is  7£,  that  of  lead  11|,  of  gold  19. 

3.  The  SPECIFIC  GRAVITY  of  the  terrestrial  globe  is  found  to  be 
about  5§ ;  that  is,  it  would  require  5|  globes  of  water,  of  the  same 
size,  to  balance  the  weight  of  the  Earth. 

4.  The  matter  composing  the  surface  of  the  globe  is  much 
less  dense,  having  a  specific  gravity  of  but  2| ;  consequently  the  in- 
terior must  be  correspondingly  denser.  Hence  we  conclude,  either 
that  metallic  substances  predominate  in  the  interior  of  the  globe, 
or  that  the  matter  therein  is  very  greatly  compressed. 

5.  The  absolute  WEIGHT  of  the  globe  is  computed  at  not  less 
than  5,852,000,000,000,000  of  tons,  a  weight  of  which  our  minds  can 
form  no  conception. 


ANALYSIS  OF   SECTION  TV. 

I.  Form  of  the  Earth. 

1.  Figure  of  the  Earth. 

2.  Deviation  from  Perfect  Sphere. 

a.  How  produced. 

b.  Proves  what. 

II.  Volume  of  Terrestrial  Globe. 

1.  Signification  of  term  Volume. 

2.  Exact  Dimensions  of  Globe. 

a.  Equatorial  Diameter. 

b.  Polar  Diameter. 

c.  Mean  Diameter. 

d.  Equatorial  Circumference. 

e.  Extent  of  Surface. 

f.  Solid  Contents. 
8.  Approximate  Dimensions. 

a.  Diameter. 

b.  Circumference. 

c.  Surface  and  solid  contents. 

III.  Mass  of  Terrestrial  Globe. 

1.  Signification  op  term  Mass. 

Examples. 

2.  Specific  Gravity  of  Globe. 

3.  Specific  Gravity  of  Surface  Regions.    Conclusion. 

4.  Absolute  Weight  op  Globe. 


V.  — THE  TERRESTRIAL  GLOBE. 

ITS  CIRCLES,   AND  SURFACE  MEASUREMENTS. 

I.  Circles  of  Position. 

1.  The  term  Circle,  in  geographical  science,  is  used  in  a  special 
sense.     The  geographical  circles  are  not  planes  cutting  the  terres- 


THE   TERRESTRIAL   GLOBE. 


trial  globe,  but  simply  lines  encircling  it.     Those  which  bisect  the 
surface  of  the  sphere  are  called  great  circles  ;  all  others  small  circles. 

2.  Great  Circles.  The  Equator  is  a  great  circle  encompassing 
the  globe  from  east  to  west,  midway  between  the  poles.  Meridians 
are  great  circles  encompassing  the  globe  from  north  to  south,  inter- 
secting at  the  poles,  and  crossing  the  equator  at  right  angles. 

3.  The  Parallels  are  small  circles  parallel  to  the  equator. 

4.  Use.  The  parallels  and  meridians,  which  are  conceived  as  in- 
tersecting at  every  point  on  the  Earth's  surface,  are  employed  in  de- 
termining the  geographical  position  of  places. 

II.  Climatic  Circles. 

1.  Climatic  Parallels.  Four  parallels  serve  not  only  to  deter- 
mine position,  but  also  to  mark  certain  important  climatic  bounda- 
ries, hence  they  may  be  distinguished  as  climatic  parallels. 

The  Tropics,  situated  23^°  from  the  equator,  mark  the  highest 
latitude  which  receives  the  vertical  rays  of  the  Sun.  Their  position 
is  fixed  by  the  inclination  of  the  Earth's  axis  23^  degrees  towards 
the  plane  of  its  orbit. 

On  the  21st  of  June  the  vertical  Sun,  in  its  diurnal  course,  passes  over  every 
point  on  the  northern  tropic  ;  on  the  22d  of  December,  over  every  point- on  the 
southern.  Twice  in  the  year  it  passes, 
in  succession,  over  every  parallel  between 
the  tropics ;  from  June  to  December  ad- 
vancing southward,  from  December  to 
June,  northward.  (See  page  70,  Positions 
of  the  Vertical  Sun.) 

The  Polar  Circles,  situated  23^° 
from  the  poles,  mark  the  limits  of 
illumination  when  the  Sun  is  ver- 
tical at  the  tropics.  Each  is  90° 
distant  from  the  tropic  on  the  op- 
posite side  of  the  equator. 

2.  The  Ecliptic  is  a  great  cir- 
cle whose  plane  coincides  with  that 
of  the  Earth's  orbit,  and  consequently  intersects  the  plane  of  the 
equator  at  an  angle  of  23^°.  It  marks  the  apparent  path  of  the 
vertical  Sun  from  tropic  to  tropic  during  the  annual  revolution  of 
the  Earth.  The  ecliptic  bisects  the  equator,  and  touches  the  two 
tropics  in  opposite  latitudes,  and  on  opposite  meridians. 

III.  Surface  Measurements. 

1.  Latitude  is  the  distance  of  a  place  from  the  equator,  measured 
upon  the  meridians.  It  is  reckoned  from  the  equator  to  each  pole  ; 
hence  there  are  90°  of  north  latitude  and  90°  of  south  latitude. 

The  length  of  a  degree  of  latitude  is  69£  miles,  or  3Jff  part  of  the 
circumference  of  the  Earth.  Near  the  poles  the  degrees  are  slightly 
longer,  owing  to  the  oblateness  of  the  sphere. 

2.  Longitude  is  the  distance  of  a  place  east  or  west  from  some 
given  meridian,  called  the  prime  meridian,  measured  on  the  equator. 
It  is  reckoned  half  way  round  the  globe  in  each  direction ;  thus 
there  arcs  180°  of  east  longitude  and  180°  of  west  longitude. 

The  length  of  a  degree  of  longitude  at  the  equator  is  69£  miles. 
As  the  parallels  constantly  diminish  in  circumference  from  the  equa- 
tor to  the  poles,  the  length  of  a  degree  of  longitude  —  ^  part  of 
each  parallel  —  must  decrease  in  like  manner.  At  the  poles,  where 
all  the  meridians  meet,  longitude  ceases.  One  minute  of  longitude 
at  the  equator  constitutes  the  geographical  or  nautical  mile  used  in 
reckoning  distances  at  sea. 


table  showing  the  circumference  of  every  fifth  paral- 
lel, AND  THE  LENGTH  OF  ITS  DEGREES  IN  ENGLISH  MILES. 


Circumference 

Length  of  degree 

Circumference 

Length  of  degree 

of  Parallel. 

of  Longitude. 

45° 

of  Parallel. 

of  Longitude. 

Equator    0° 

24,899 

69.164 

17,636 

48.988 

5 

24,805 

68.909. 

50 

16,036 

44.545 

10 

24,523 

68.120 

55 

14,314 

39.760 

15 

24,056 

66.829 

60 

12,481 

34.669 

20 

23,406 

65.018 

65 

10,552 

29.310 

25 

22,580 

62.721 

70 

8,541 

23.726 

30 

21.581 

59.948 

75 

6,465 

17.957 

35 

20,418 

56.718 

80 

4,338 

12.049 

40 

19,100 

53.055 

85 

2477 

6.048 

4.", 

17,636 

48.988 

Pole  90 

0,000 

0.000 

The  prime  meridian  commonly  employed  by  the  English  and  the 
Americans,  is  that  of  the  National  Observatory  at  Greenwich,  near 
London.  The  French  and  German  geographers  also  use  the  merid- 
ian of  the  observatory  at  Paris,  and  the  Americans  often  employ  that 
of  the  National  Observatory  at  Washington.  Paris  is  the  most 
easterly,  Greenwich  being  2°  20'  22"  west  of  Paris,  and  Washington 
77°  02'  47"  west  of  Greenwich. 

The  meridian  of  20°  west  from  Paris,  falling  somewhat  beyond 
Ferro,  the  most  westerly  of  the  Canary  Islands,  is  also  employed  as 


NOR7V; 


MERIDIANS  AND  PARALLELS. 


CLIMATIC  CIRCLES. 


prime  meridian  ;  and,  lying  at  the 
west  of  all  the  lands  of  the  Old 
World,  it  has  been  generally 
adopted  as  the  most  appropriate 
boundary  between  the  eastern  and 
the  western  hemisphere. 

IV.   Relation  of  Longitude   to 
Time. 

1.  Computation  of  Longi- 
tude by  Time.  Since  any  given 
point  on  the  Earth's  surface  passes 
through  360°  of  longitude — one 
entire  rotation  — in  24  hours,  it  must  pass  through  =\8,°-°,  or  15°,  in 
one  hour ;  and  1°  in  TV  of  one  hour,  or  4  minutes.  Hence  if  the 
difference  in  time  marked  at  two  places  be  known,  their  difference 
in  longitude  can  at  once  be  ascertained,  and  vice  versa. 

Suppose,  for  example,  an  accurate  time-keeper,  marking  New  York  time,  be 
taken  to  London;  it  will  be  found  four  hours  and  fifty-six  minutes,  or  296  minutes, 
slower  than  London  time.  Hence  the  difference  in  longitude,  expressed  in  degrees, 
must  be  one  fourth  this  number,  or  2$&  =  74°. 

2.  Difference  of  Time  marked  at  the  same  Moment. 
The  moment  at  which  the  Sun  crosses  the  meridian  of  a  given  place, 
is  noon  or  mid-day  at  that  place.  The  meridian  which  is  90°,  or  a 
quartet  of  a  rotation,  to  the  eastward  has  six  hours  later  time 
at  the  same  moment ;  and  one  which  is  180°  east,  twelve  hours  later. 
Meridians  at  corresponding  distances  to  the  westward  have  a  corres- 
ponding number  of  hours  earlier  time ;  so,  in  proportion,  of  less  dis- 
tances. 

The  diagram  below  illustrates  the  different  time  marked  in  different  longitudes 
at  the  same  moment :  — 


West. 


180° 


0° 


East. 
90° 


180° 


12  A.  M. 
Monday,  or  mid- 
night of  Sunday. 


6  A.  M. 
Monday. 


Noon 
of  Monday. 


6  P.  M. 

Monday. 


12  P.  M. 

Midnight  of 

Monday. 


Thus  it  happens  that  mariners,  starting  from  a  given  point  and  sailing  around 


THE   TERRESTRIAL   GLOBE   A  MAGNET. 


the  world  to  the  west,  lose  a  day  in  making  the  circumnavigation  ;  while  in  sailing 
eastward  they  gain  a  day.  To  correct  this  error  in  the  former  case  they  must,  at 
some  point,  add  one  day  to  their  reckoning  of  time,  making  the  date  24  hours  later, 
and  in  the  latter  case  drop  a  day. 


ANALYSIS  OF  SECTION  V. 

I.  Circlet*  of  Position.    ■ 

1.  Geographical  Use  of  the  term  Circle. 

2.  Great  Circles. 

a-  Equator, 
b.  Meridians. 

3.  Parallels. 

4.  Use. 

II.  Climatic  Circles. 

1.  Parallels. 

(  Definition  of. 
'  )  Position  to  what  due. 

u    t»  .      n-    ,       ( Definition  of. 

b.  Polar  Circles,  i  „    ...      .        .  . 

/  Position  in  reference  to  tropics. 

2.  Ecliptic. 

a.  Definition. 

b.  What  it  marks. 

c.  Relation  to  tropics  and  equator. 

III.  Surface  Measurements. 

1.  Latitude. 

a.  Definition. 

b.  Number  of  degrees. 

c  Length  of  degrees.    Exception. 

2.  Longitude. 

a.  Definition. 

b.  Number  of  degrees. 

c.  Length  of  degrees  at  the  equator.    How  varying. 
( Locations  of. 


d.    Prime  meridians. 


/  Relative  situation. 


IV.  Relation  of  Longitude  to  Time. 

1.  Computation  op  Longitude  prom  Difference  op  Time. 

a.  Basis  of  computation. 

b.  To  convert  difference  of  time  to  difference  of  longitude. 

c.  To  convert  difference  of  longitude  to  difference  of  time. 
2   Differences  op  Time  marked  at  same  Moment. 

a.  Variation  eastward. 

b.  Variation  westward. 

c  Variations  in  circumnavigating  the  globe.    How  corrected. 


VI.  — THE    TERRESTRIAL   GLOBE   A   MAGNET. 

I.  Magnetism. 

1.  A  Magnet  is  a  body  which,  has  the  property  of  attracting  iron  ; 
and  the  term  Magnetism  is  applied  to  the  cause  of  this  attraction 
and    the   resulting    phenomena. 

Magnetism  was  known  to  the 
ancients,  having  been  first  ob- 
served in  the  loadstone,  a  species 
of  iron  ore  found  in  abundance 
near  the  city  of  Magnesia,  in 
Asia  Minor,  whence  the  magnet 
takes  its  name. 

2.  Abtificial*  Magnets  may 
be  readily  produced  by  friction. 
A  bar   of   steel  rubbed  with  a 

natural,    or   other,    magnet    ac- 

.  mariner's  compass. 

quires  permanent  magnetic  prop- 
erties.    The  magnetic  needle  is  an  artificial  magnet  suspended  upon 
a  pivot,  so  as  to  move  freely  in  any  direction.     The  Chinese  availed 
themselves  of  it,  in  traversing  the  trackless  deserts  of  central  Asia, 
long  before  the  use  of  the  compass  was  known  in  Europe. 

The  mariner's  compass  is  a  magnetic  needle  attached  to  the  lower  side  of  a  leaf 
of  mica,  on  which  is  traced  a  star  with  32  points,  marking  the  eight  rhumbs,  the 
semi-rhumbs,  and  the  quarters  of  the  wind.  The  compass  is  suspended  in  a  box 
»o  as  to  preserve  a  horizontal  position  in  spite  of  the  motion  of  the  ship. 


II.  Properties  of  Magnets. 

1.  The  magnetic  force  is  not  equally  distributed  throughout 
the  magnet,  but  is  greatest  at  the  extremities,  diminishing  towards 
the  centre,  where  it  ceases.  Every  magnet,  therefore,  has  two  poles, 
at  opposite  extremities  —  one  positive,  the  other  negative  —  with  a 
neutral  line  in  the  centre.  They  are  distinguished  as  the  north 
pole  and  the  south  pole.  Poles  of  the  same  name  repel,  and  those 
of  contrary  name  attract  each  other.  When  a  magnet  is  broken, 
each  half  becomes  itself  a  complete  magnet. 

The  illustration  below  represents  a  magnet  which  has  been  plunged  into  a  basin 
of  iron  filings.  These  cluster  in  great  numbers  around  the  ends,  each  piece 
in  contact  with'  trie  magnet  attracting  others ;  but  they  are  absent  from  the  centre, 
where  the  opposite  poles  neutralize  each  other. 


A  MAGNET. 


2.  The  Earth  a  Magnet.  The  terrestrial  globe  exhibits  the 
properties  of  a  magnet  in  the  directing  power  it  exerts  upon  the 
magnetic  needle.  Whether  on  sea  or  land,  on  mountains  or  in  deep 
valleys,  a  magnetic  needle,  if  free  to  move,  always  so  adjusts  itself 
that  its  poles  point  in  a  definite  direction,  along  a  line  which  is  vir- 
tually north  and  south. 

That  pole  of  the  needle  which  is  attracted  by  the  north  mag- 
netic pole  of  the  Earth,  must  be  in  an  opposite  magnetic  condition. 
Hence  it  is  the  proper  south  pole  of  the  magnet,  but  since  it  points 
toward  the  geographical  north,  it  is  designated  the  north  "pole. 

3.  The  Magnetic  Poles  op  the  Earth  do  not  coincide  with 
the  poles  of  rotation,  but  are  found  about  20°  from  them.  Neither 
do  the  magnetic  meridians,  which  pass  through  the  magnetic  poles 
of  the  Earth  and  those  of  the  needle,  generally  coincide  with  the 
geographical  meridians,  for  the  needle  rarely  points  due  north. 

III.  Magnetic  Variation  or  Declination. 

1.  Magnetic  variation,  or  declination,  is  the  difference  be- 
tween the  true  north  and  the 
direction  indicated  by  the  mag- 
netic needle.  The  declination  is 
said  to  be  east  or  ivest,  according 
as  the  north  pole  of  the  needle  is 
east  or  west  of  the  geographical 
meridian. 

By  connecting  all  points  which  have 
equal  declination,  we  obtain  a  system  of 
lines  which  show  at  a  glance,  as  in  the 
map  on  page  9,  the  extent  to  which  the 
needle  deviates  from  the  true  north,  in 
all  parts  of  the  world.  The  eastern 
declination  is  distinguished  on  this 
map  by  dotted  Jines  and  a  light  brown  color ;  the  western  by  solid  lines  in  a 
blue  ground.  The  degree  of  variation  is  shown  by  figures  attached  to  the 
lines. 

The  lines  of  equal  declination,  at  all  points  on  any  one  of  which  the  needle  pre- 
serves one  unvarying  direction,  must  not  be  confounded  with  magnetic  meridians 
which,  passing  through  the  poles  of  the  needle,  would  show  what  that  direction 
actually  is. 

In  certain  parts  of  the  globe  the  magnetic  and  geographical  me- 
ridians coincide.     These  places  are   connected  by  an   irregularly 


POCKET   COMPASS. 


10 


TEMPERATURE    OF   THE   TERRESTRIAL   GLOBE. 


parture  from  a  horizontal  position,  of  a  needle  suspended  so  as  to  move  freely  in  a 
vertical  plane,  and  adjusted  in  the  magnetic  meridian.  In  the  northern  hemi- 
sphere the  north  pole  of  the  needle  dips,  in  the  southern  the  south  pole. 

2.  Degree  of  Dip.  The  magnetic  inclination  is  greatest  at  the  magnetic  pole, 
where  the  needle  assumes  a  vertical  position.  Passing  towards  the  equator  the 
inclination  becomes  less  and  less,  until  a  line  is  reached  in  which  the  needle  is 
horizontal. 

The  line  of  no  inclination  constitutes  a  magnetic  equator,  and  the  lines  of  equal 
inclination,  magnetic  parallels.  They  coincide  in  a  remarkable  manner  with  the 
isolhermals,  or  lines  of  equal  mean  temperature  on  the  globe,  thus  indicating  a 
close  connection  between  the  distribution  of  magnetism  and  of  solar  heat. 

2.  Variations.  Magnetic  inclination,  like  declination,  is  subject  to  both  pe- 
riodical and  secular  variations.     The  later  is  shown  by  the  following  table :  — 

INCLINATION   OBSERVED   AT  PARIS. 


1371 75°  W 

1780 71°  48' 

1798 69°  51' 


Year. 


Inclination 


1806 69°  12/ 

1814 68°  W 

1820 68°  20' 


Year. 


Inclination. 


1825 68°  OCC 

1831 67°  40' 

1853 66°  28' 


Since  the  year  1G71,  it  appears,  the  inclination  of  the  needle  at  Paris  has  stead- 
ily decreased  from  three  to  five  minutes  per  year. 


ANALYSIS  OF   SECTION   VI. 


I0  Magnetism. 


1.  Phenomena  exhibited. 

a.  Where  first  observed. 

b.  Origin  of  name  magnet. 

2.  Artificial  Magnet. 

a.  How  produced. 

b.  Magnetic  needle. 

c.  Mariner's  compass. 


II.  Properties  of  Magnets. 

1.  Polarity. 


a.  How  exhibited. 

b.  Poles  of  magnet. 

c.  Subdivision  of  magnet. 

2.  The  Earth  a  Magnet. 

a.  Property  of  magnet  exhibited  by  it. 

b.  Position  of  magnetic  needle. 

c.  Relative  position  of  poles  of  needle  and  of  Karth 

3.  Magnetic  Poles  op  Earth. 

a.  Their  geographical  position. 

b.  Magnetic  meridians. 

c.  Direction  of  magnetic  needle. 


ill.  Magnetic  Declination. 

1.  Definition. 


a.  Lines  of  no  declination. 


b.  Direction  of  declination. 


Definition.    Number 
Position. 

East  hemisphere. 
West  hemisphere 


2.  Secular  Variation. 

a.  Definition. 

b    Results  of  observation  in  Paris. 

(1.)  Extent  of  variation. 
(2.)  Minimum  and  maximum. 
(3.)  Direction  of  change  before  1814. 
(4.)  Direction  of  change  since  1814. 
(5.)  Rate  of  change. 
8   Minor  Variations. 

IV.  Magnetic  Inclination. 

1-  Definition. 

2.  Degree  of  Dip. 

a.  How  varying. 

b,  Magnetic  equator  and  parallels. 

3.  Variation  of  Inclination. 

a.  Kinds  of  variation. 

h.  Results  of  observation  in  Paris. 


VII.  —  TEMPERATURE  OF  THE  TERRESTRIAL  GLOBE. 

I.  Evidences  of  Internal  Heat. 

That  the  interior  of  the  terrestrial  globe  maintains  a  high  temper- 
ature, independently  of  the  influence  of  the  Sun  upon  the  surface,  is 
proved  by  a  variety  of  phenomena. 

1.  Waem  Springs  are  numerous  in  nearly  all  parts  of  the  Earth, 
varying  in  heat  from  a  degree  but  slightly  above  the  mean  annual 
temperature  of  the  place  where  they  occur,  to  the  boiling  point. 

The  temperature  of  ordinary  springs  and  wells  does  not  differ  materially  from 
the  mean  annual  temperature  of  the  ground  and  the  air  above  it,  and  is  compara- 
tively uniform  throughout  the  year.  Thus  in  winter  the  water  is  warmer  than 
the  air  ;  in  summer,  colder. 

Explanation  of  the  cat.  The 
geysers  seem  to  be  due  to  the 
unequal  heating  of  a  column  of 
water  in  an  open  vertical  shaft, 
traversing  hot  volcanic  strata. 

Steam  escapes  when  the  tem- 
perature of  the  water  enables 
its  expansive  force  to  overcome 
the  pressure  of  the  atmosphere, 
viz.,  at  212°  Fahr.,  at  sea  level. 
But  at  the  bottom  of  a  shaft  of 
<>8  feet,  for  instance,  the  press- 
ure being  equal  to  three  atmos- 
pheres, a  much  higher  degree 
of  heat  is  required.  When  this 
is  reached,  steam  is  formed, 
which,  in  ascending,  partially 
expels  the  water  from  the  shaft. 
The  pressure  being  thus  re- 
lieved, new  masses  of  steam  de- 
velop rapidly,  and  the  explo- 
sions become  so  frequent,  and 
the  successive  jets  so  powerful, 
as  to  form  a  continuous  column 
of  boiling  water  and  vapor  rising 
in  the  air.  When  the  explosions 
cease,  the  water,  now  cooled, 
falls  back  into  the  shaft,  and 
after  a  time  of  rest  the  process 
recommences. 

The  correctness  of  this  view 
is  confirmed  by  the  fact  that  the 
temperature  within  the  shaft 
increases  towards  the  bottom. 
In  the  Great  Geyser  of  Iceland. 
Bunsen  found  the  temperature 
at  the  surface  of  the  water  to 
be  from  169°  to  192°  Fahr.  ;  but 
at  the  depth  of  72  feet  it  was 
261°  before  an  eruption,  and 
2.")  2°  after,  or  from  40°  to  50° 
higher  than  boiling  water. 

TUB  GIANTESS  GEYSER.    (See  page  11.) 

Springs,  of  whatever  temperature,  are  simply  the  return  of  water 
to  the  surface,  after  circulating  among  the  Earth's  strata1  at  a 
greater  or  less  depth.  When  it  entered  the  ground  it  could  not 
have  been  warmer  than  the  surrounding  atmosphere  ;  hence  the 
higher  temperature  of  warm,  or  thermal,  springs  must  have  been 
imparted  to  the  water  by  the  strata  among  which  it  has  circulated. 

2.  Active  Volcanoes  are  found  in  all  latitudes,  ejecting,  from 
time  to  time,  streams  of  red  hot  lava ;  hence  it  is  evident  that  at 


i  Beds  of  earth  or  rock,  formed  by  natural  causes,  and  usually  consisting  of  a  series  of  layers. 


TEMPERATURE   OF   THE   TERRESTRIAL   GLOBE. 


11 


some  place  within  the  Earth  there  exists  a  degree  of  heat  sufficient 
to  melt  even  the  solid  rock. 

3.  Artesian  Wells  and  Mines  permit  the  actual  observation  of 
the  internal  temperature  of  the  Earth  to  the  depth  of  about  3,000 
feet,  and  the  results  corroborate  the  inference  drawn  from  ther- 
mal springs  and  active  volcanoes. 

II.  Thermal  Springs. 

1.  Thermal  springs  are  most  numerous  in  mountainous  or  volcanic 
regions,  where  the 

strata  are  most  dis- 
turbed, broken, 
and  creviced. 

Europe  is  proba- 
bly the  richest  of  the 
continents  in  warm 
springs.  Over  800 
have  been  de- 
scribed in  France, 
400  in  Spain,  and 
a  still  greater 
number  in  Ger- 
many, Bohemia, 
Switzerland,  Italy, 
and  England,  some 
of  which  have  a 
temperature  as 
high  as  180°  Fahr. 

2.  Intermittent 
spouting  springs, 
or  Geysers^  — 
whose  tempera- 
ture    reaches     or 

even  somewhat  exceeds  212°  Fahr.  — are  found  in  Iceland,  also  near 
tile  head  waters  of  the  Yellowstone  River  in  the  Rocky  Mountains, 
and  in  New  Zealand.     They  are  all  in  volcanic  districts. 

The  Great  Geyser  of  Iceland  is  the  most  famous  of  these  intermittent  springs.  It 
ejicts  at  intervals,  from  a  vertical  chimney,  a  column  of  water  sometimes  ten 
feet  in  diameter  and  nearly  a  hundred  feet 
in  height.  Even  more  remarkable  are  the 
Giantess,  throwing  a  column  of  water  over 
two  hundred  feet  high,  the  Grand  Geyser, 
and  other  springs  in  the  extensive  geyser 
basin  of  the  upper  Yellowstone,  in  Montana 
Territory.     (See  explanation, page  10.) 

The  so  called  geysers  of  California, 
near  Mount  St.  Helena,  north  of  San 
Francisco  Bay,  are  simple  boiling 
springs,  neither  spouting  nor  intermit- 
tent. Boiling  springs  also  occur  in 
Venezuela  and  the  Andes  of  Peru, 
South  America ;  in  Japan,  and  in  va- 
rious other  regions  both  in  the  New  World  and  the  Old. 

3.  Thermal  springs  usually  are  highly  impregnated  with  mineral 
substances,  a  condition  facilitated  by  the  increased  solvent  power  of 
warm  water. 

Mineral  springs  are  classified  according  to  the  gaseous  or  the  mineral  substances 


THE  GREAT   GEYSER   BASIN  OF  THE  UPPER  YELLOWSTONE. 


1  From  an  Icelandic  word  which  signifies  raging  or  spouting.     It  is  applied  to  intermittent 
boiiing  springs  whose  waters  burst  out  at  intervals  with  great  force. 


they  contain.  The  principal  classes  are  —  (1.)  The  acidulous,  containing  large 
quantities  of  carbonic  acid  gas,  as  the  waters  of  Pyrmont  and  Seltz  in  Germany 
Spa  in  Belgium,  and  Vichy  in  France.  (2.)  The  sulphurous,  as  the  White  Sul- 
phur springs  in  West  Virginia,  and  the  Saratoga  springs  in  New  York.  (3.)  Saline 
springs,  abounding  in  common  salt,  numerous  in  all  parts  of  the  world.  (4.)  Chal- 
ybeate springs,  containing  salts  of  iron,  abundant  in  all  countries  rich  in  iron 
mines.  (5.)  Complex  springs,  containing  a  variety  of  salts  without  the  special 
preponderance  of  any  one. 

III.  Artesian  Wells  and  Mines. 

1.  Formation  of  Artesian  Wells.    The  commonly  received 

theory  supposes  a 
geographical  basin, 
of  greater  or  less 
extent,  in  which 
two  impermeable  2 
strata,  like  clay, 
inclose  between 
them  a  permeable 
stratum,  like  sand 
or  gravel.  The 
rain  water,  falling 
on  the  latter  where 
it  reaches  the  sur- 
face of  the  ground, 
filters  through  it, 
following  the  inch- 
nation  and  accu- 
mulating in  the 
lower  levels,  where 
it  is  retained  by 
the  impermeable 
strata  above  and 
below.  (Such  a 
formation  is  shown 
in  the  small  cut  below,  of  a  well  in  the  London  basin.) 

If  the  drill,  in  boring  a  well,  reaches  such  a  water-bearing  bed  be- 
low its  highest  level,  the  water  rises  in  the  well  to  that  level ;  or  if 
the  highest  level  of  the  bed  be  above  that  of  the  mouth  of  the  well, 
the  water  spouts  out  like  a  fountain. 

The  artesian  well  is  so  called  from 
the  province  of  Artois,  in  France, 
where  such  wells  have  long  been  in  use. 
2.  Observations  in  Wells. 
(1.)  How  Made.  Observations  on 
temperature  are  made  with  self-reg- 
istering thermometers,  lowered  to 
different  depths.  They  furnish  the 
means  of  ascertaining  the  rate  of  in- 
crease in  the  internal  temperature  of 
the  globe,  starting  from  the  mean  an- 
nual —  or  invariable  —  temperature 
of  the  ground,  which  is  found  at  a 
greater  or  less  distance  below  the  surface. 

The  surface  layers  of  the  soil  are  affected  by  the  varying  heat  of  the  seasons, 
being  colder  in  winter  and  warmer  in  summer ;  but  the  variations  gradually 
diminish  below  the  surface,  to  a  point  at  which  the  temperature  is  constant 
throughout  the  year.  This  point  gives  the  mean  annual  temperature  of  the 
ground,  which  is  equal  to  that  of  the  air  above.  In  the  equatorial  regions,  where 
the  seasons  are  nearly  uniform  in  temperature,  it  is  found  a  few  feet  below  the 

2  Not  permitting  the  passage  of  a  fluid  through  its  substance. 


F  ARTESIAN  WELLS. 


12 


RESULTS   OF  INTERNAL   HEAT.  — VOLCANIC  PHENOMENA. 


surface ;  but  it  descends,  with  increasing  latitude,  as  the  difference  between  the 
summer  and  winter  temperature  of  the  air  increases.  In  middle  latitudes  it  is 
found  about  sixty  or  eighty  feet  below  the  surface. 

(2.)  Where  Made.  Among  the  wells  in  which  valuable  observa- 
tions  have  been  made  are  the  following:  one  at  Columbus,  Ohio, 
2,775  feet  deep;  at  Louisville,  Kentucky,  2,086  feet;  at  St.  Louis, 
Missouri,  2,199.>  feet ;  at  Q-renelle,  near  Paris,  2,021  feet  deep ;  at 
Neu-Salziverh,  in  Germany,  2,288  feet;  and  at. Mouillelonge,  in  cen- 
tral France,  2,677  feet. 

(3.)  Result  of  Observations.  The  following  table,  giving  the 
result  of  observations  in  the  above  named  wells,  shows  that  the  tem- 
perature invariably  increases  with  increasing  depth,  but  the  rate 
of  increase  is  different  in  different  wells. 


Well 

Depth  of  observation. 

Temp.  Fahr. 

Rate  of  Increase. 

Columbus, 

2,775 

88.0° 

1°  for  73  feet. 

Louisville, 

2,086 

82.5° 

loi<    72     " 

St.  Louis, 

2,199 

8O.40 

1°"    88     " 

Mouillelonge, 

2,677 

101.0° 

1°"    51     " 

Neu-Salzwerk, 

2,288 

92.5° 

1°"    55     " 

Grenelle, 

1,798 

82.4° 

1°"    58     " 

3.  Observations  in  Mines  exhibit  similar  results.  The  increase 
of  heat  downward  is  constant,  but  the  rate  of  increase  often  differs 
widely  even  in  mines  not  very  far  apart,  owing  probably  to  differ- 
ence in  the  nature  of  the  rocks. 

In  the  Prussian  mines,  where  observations  have  been  made  with  the  greatest 
care,  the  most  rapid  rate  observed  is  1  °  Fahr.  for  2  7  feet  of  descent ;  and  the  slowest, 
1°  for  197  feet,  the  average  being  1°  for  92  feet.  In  the  mines  of  Saxony  the  ave- 
rage increase  is  1°  for  72  feet;  in  six  of  the  largest  mines  in  England,  1°  for  44 
feet;  and  in  the  coal  mines  of  Virginia,  1°  for  60  feet.  Even  the  frozen  soil 
of  Siberia,  having  a  tempemture  near  the  surface  of  but  10°,  shows  a  steady  in- 
crease downward  at  a  rate  which  would  free  the  soil  from  frost  at  the  depth  of 
600  feet. 

4.  The  average  of  all  known  observations,  whether  in  artesian 
wells  or  mines,  shows  an  increase  of  heat  towards  the  interior  of  the 
Earth,  at  the  very  rapid  rate  of  about  1°  Fahr.  for  every  55  feet. 

5.  Conclusion.  If  this  ave- 
rage rate  continues  without  in- 
terruption, the  temperature  of 
boiling  water  must  be  reached  at 
the  depth  of  9,000  feet,  or  less 
than  two  miles  from  the  surface  ; 
and  at  the  depth  of  thirty  miles 
the  heat  would  be  sufficient  to 
melt  the  most  refractory  sub- 
stances. 


analysis  of  section  vii. 

I.  Evidences  of  Internal  Heat  of  Globe. 

1.  Warm  or  Thermal  Springs. 

a.  Distribution  and  temperature. 

b.  Source  of  waters. 

c.  Source  of  warmth. 

2.  Active  Volcanoes  —  conclusion  prom. 

3.  Artesian  Wells  and  Mines. 

a.  Depth  of  observations. 

b.  Result  of  observations. 

II.  Thermal  Springs. 


1.  Situation  and  Temperature. 

a.  Where  most  numerous. 


b.  European  springs. 


i  Number. 


'  I  Temperature. 

2.  Geysers,  how  explained. 

a.  Temperature. 

b.  Where  found. 

c.  Great  geyser  described. 

d.  Other  remarkable  geysers.    Geyser*  of  California. 

3.  Waters  of  Thermal  Springs. 

a.  Character. 

b.  To  what  due. 

c.  Classification. 


III.  Artesian  Wells  and  Alines. 


a  a  Strata  not  volcanic. 
d  d  Crater. 


There  is,  however,  some  rea- 
son to  believe  that  the  rate  of 
increase  becomes  slower  at  greater 

depths ;  and  that  the  solid  crust  of  the  Earth,  inclosing  the  melted 
mass,  has  a  thickness  varying  from  50  to  100  miles. 

The  active  volcanoes,  pouring  out  torrents  of  fiery  lava,  demon- 
strate that  the  conclusion  drawn  from  observations  of  the  Earth's  in- 
ternal temperature  is  not  a  fanciful  one  ;  for  the  volcanic  phenom- 
ena are  too  general  and  too  closely  connected  with  the  great  frac- 
tures of  the  Earth's  crust  to  be  accounted  for,  as  has  been  attempted, 
by  merely  local  chemical  causes. 


FORMATION  AND   STRUCTURE  OF   VOLCANIC  CONES. 

mouth  of  the  shaft 


1.  Formation  of  Wells  described. 

a.  Supposed  conditions 

b.  Effect  of  drilling. 

c.  Origin  of  name. 
3-  Observations  in  Wells. 

a.  How  made. 

b.  Temperature  of  ground. 

c.  Mean  annual  temperature  found  where. 

d.  Observations.    Where  made. 

e.  Results. 

a.  Observations  in  Mines.    Examples. 

4.  Average  Result  of  all  Observations. 

5.  Conclusion  from  all  Observations. 

a.  Temperature  at  9,000  feet. 

b.  Temperature  at  thirty  miles. 

c.  Probable  thickness  of  Earth's  crust. 

d.  Conclusion  how  sustained. 


VIII.  — RESULTS    OF  INTERNAL   HEAT  —  VOLCANIC 

PHENOMENA. 

I.  Nature  and  Formation  of  Volcanoes. 

1.    A  volcanic  mountain  is  usually   of  conical  form,  with  a 

circular  basin  or  depression,  called 
a  crater,  at  its  summit.  In  the 
centre  of  the  crater  is  the  mouth 
of  a  perpendicular  shaft  or  chim- 
ney, which  emits  clouds  of  hot 
vapor  and  gases  ;  and  in  periods 
of  greater  activity,  ejects  ashes, 
fragments  of  heated  rock,  and 
streams  of  fiery  lava. 

2.  The  volcanic  cone  is 
FORMED  by  the  accumulation  of 
the  ejected  materials,  in  a  series 
of  concentric  layers,  around  the 
These  layers  are  distinctly  visible  on  the  inner 
walls  of  the  crater,  and  in  every  part  of  the  mass  which  is  open  to 
observation  through  crevices. 

This  mode  of  formation  not  only  explains  the  conical  form  of  vol- 
canoes, but  distinguishes  them  from  the  mountains  and  mountain 
chains  which  are  the  result  of  the  folding  or  uplifting  of  the  solid 
crust  of  the  Earth,  and  which  form  the  skeletons  of  the  continents 
and  islands. 


c  c  Lava  and  ashes. 

e  Cone  of  eruption. 
//  Lateral  eruptions,  parasitic  cones. 


Chimney. 


RESULTS  OF  INTERNAL  HEAT.  —  VOLCANIC  PHENOMENA. 


13 


«3.  The  form  of  VOLCANIC  cones  appears  to  depend  upon  the 
ative  fluidity  of  the  ejected  materials  by  which  they  were  built  up. 
In  general  the  more  liquid  the  lava,  and  the  smaller  the  quantity 
of  solid  materials,  the  broader  and  flatter  are  the  cones.  The  vol- 
canoes of  the  Sandwich  Islands,  noted  for  the  liquidity  of  their  lavas 
and  an  almost  entire  absence  of  ashes,  are  remarkable  for  their 
flattened  form  and  the  slight  inclination  of  their  slopes. 

Dana  estimates  tlie  average  slope  of  Mauna  Loa  to  be  only  from  six  to  eight 
degrees.  A  horizontal  section  1,800  feet  below  the  summit,  would  be  nearly 
twenty  miles  broad;  and  the  top,  in  which  the  crater  is  sunk,  though  nearly 
1  1,000  feet  in  elevation,  is  a  plain  so  level  that  the  surrounding  ocean  cannot 
be  perceived  from  it. 

In  volcanoes  where  the  lavas  are  less  liquid  and  ashes  abound,  as 
in  Vesuvius  and  Etna,  the  form  is  more  conical  and  the  slopes  are 
more  steep,  being  from  twenty  to  thirty-five  degrees.  Volcanoes 
which  eject  only  ashes  and  fragments  of  rock,  as  those  of  the  Andes, 
art;  still  more  steep  and  pointed  in  form  ;  as  shown  in  the  cones  of 
Cotopaxi  and  Arequipa.  In  the  volcanoes  of  Iceland,  where  the 
lava  is  viscous  and  alter- 
nates with  ashes,  the  form 
resembles  a  dome. 

4.  Volcanic  Pboducts. 
Volcanic  ashes,  when  ex- 
amined under  a  micro- 
scope, are  found  to  be 
simply  pulverized  lava, 
frequently  in  minute 
crystals,  and  bear  no  re- 
semblance to  ashes  in  the 
ordinary  sense  of  the 
term. 

They  occasionally  form 
a  line  powder  which  is  car- 
ried by  the  wind  to  a  dis- 
tance id'  hundreds  of  miles. 
Coarser  materials  take  the 
name  of  volcanic  sand. 

Irregular  fragments  of  view  of 

solidified  lava,  of  all  sizes,  including  large  pieces  of  the  walls  of  the 
erat.r,  are  at  times  ejected  with  great  violence.  Humboldt  speaks 
of  a  mass  of  several  tons  weight  which  was  thrown  to  the  distance 
of  seven  miles  from  the  crater,  in  an  eruption  of  Cotopaxi. 

The  lava  stream,  when  flowing  white  hot  from  the  crater,  is  not 
unlike  a  jet  of  melted  iron  escaping  from  a  furnace,  and  moves  at 
first  with  considerable  rapidity.  It  soon  cools  on  the  surface,  and 
becomes  covered  with  a  hard,  black,  porous  crust,  while  the  interior 
remains  melted  and  continues  to  flow.  If  the  stream  is  thick  the 
lava  may  be  found  still  warm  after  ten  or  even  twenty  years. 

5.  The  amount  of  matter  ejected  by  volcanoes  is  very  great. 
The  whole  island  of  Hawaii,  the  largest  of  the  Sandwich  Islands, 
seems  to  be  only  an  accumulation  0f  lava  thrown  out  by  its  four 
craters.  All  high  oceanic  islands  are  of  the  same  character. 
Iceland,  with  an  area  of  40,000  square  miles,  is  a  vast  table  land 
from  3,000  to  5,000  feet  in  elevation,  composed  of  volcanic  rock  sim- 
ilar to  the  lavas  still  ejected  by  its  numerous  volcanoes. 

Tb»  formation  of  a  new  volcano  which  occurred  in  Mexico  in  1 759,  and  has  been 
described  by  Humboldt,  exhibits  the  magnitude  of  volcanic  eruptions.  In  a  fertile 
and  highly  cultivated  plain,  with  an  elevation  of  2,000  feet,  the  ground  was  rent ; 
and  at  points  along  the  fissure  were  ejected  an  immense  amount  of  lava  and  frag- 
ments of  rock,  which  accumulated  in  six  distinct  volcanoes.  The  central  one, 
iorvllo,  rises  1,G00  feet  above  the  plain;  and  all  rest  on  a  bed  of  volcanic  rock 


studded  with  small  steaming  cones,  and  gently  rising  towards  the  centre  where 
it  is  500  feet  thick.  This  region,  covering  an  area  of  four  square  miles,  now 
bears  the  name  of  the  Malpays,  or  "  bad  lands." 

6.  The  number  of  volcanoes,  active  and  extinct,  is  variously 
estimated.  Dr.  Fuchs  enumerates  672,  of  which  270  are  active. 
Of  the  active  volcanoes  175  are  on  islands,  and  95  on  the  continents 
near  the  sea  shores. 

7.  The  height  of  volcanoes  varies  from  submarine  cones  to 
an  elevation  23,000  feet  above  the  level  of  the  sea.  If  such  volca- 
noes as  Mauna  Loa,  14,000  feet  high,  have  their  base  at  the  bottom 
of  the  deep  waters  which  surround  them,  the  total  elevation  of  such 
a  structure  may  reach  that  of  the  highest  mountains  on  the  globe. 

II.  Volcanic  Activity  —  Vesuvius. 

Nearly  all  active  volcanoes  have  intervals  of  comparative  repose,  in- 
terrupted by  periods  of  increased  activity  which  terminate  in  a  violent 
ejection  of  matter  from  the  interior,  during  which  the  volcano  is  said 

to  be  in  a  state  of  erup- 
tion. 

The  phenomena  which 
characterize  these  differ- 
ing phases  of  volcanic  ac- 
tivity may  be  best  made 
clear  by  describing  them 
as  actually  observed  in 
Vesuvius,  one  of  the  most 
carefully  studied  and  most 
active  volcanoes  of  mod- 
ern times. 

This  remarkable  moun- 
tain may  be  considered  as 
typical,  for  the  phenomena 
exhibited  by  it  are  more 
or  less  common  to  all  ac- 
tive volcanoes. 

Each  volcano  may  dif- 
jorcllo.  fer  from  this  in  the  rela- 

tive amount  of  ashes  and  broken  fragments  compared  to  the  liquid 
lava ;  in  the  violence  and  frequency  of  the  eruptions  ;  the  form  and 
size  of  the  crater ;  the  greater  or  less  steepness  of  the  cone ;  the 
composition  of  the  lavas,  and  other  secondary  circumstances  :  but  the 
general  course  and  character  of  the  phenomena  show  a  remarkable 
similarity. 

Even  submarine  volcanoes  do  not  seem  to  differ  materially  from 
others,  though  the  arrangement  of  the  ejected  materials,  in  the  for- 
mation of  a  submarine  cone,  is  no  doubt  modified  to  a  certain  extent. 


III.  Vesuvius,  the  Typical  Volcano. 

1.  Situation  and  Form.  Vesuvius  is  a  solitary  mountain  rising  to  the 
height  of  nearly  4,000  feet,  from  the  midst  of  a  highly  cultivated  plain  which  bor- 
ders upon  the  shores  of  the  Bay  of  Naples.  Though  the  mountain  has  a  regular 
conical  form,  two  summits,  very  nearly  equal  in  height,  are  visible  from  Naples  — 
Monte  Somma,  on  the  north,  and  Vesuvius  proper  on  the   south. 

Monte  Somma  is  only  the  northern  half  of  the  crater-rim  of  the  old  Vesuvius, 
the  southern  half  of  which  was  destroyed  in  the  year  79  a.  d.,  in  which  occurred 
the  first  eruption  of  that  volcano  in  historical  times.  Vesuvius  proper,  is  the  new 
cone  which  has  gradually  grown  out  of  the  old  crater,  by  the  ejection  of  materials 
in  subsequent  eruptions.  After  an  eruption  the  energies  of  the  volcano  seem  to 
be  exhausted,  and  it  enters  into  a  state  of  relative  repose. 

2.  State  of  Repose.     At  the  close  of  the  great  eruption  of  1822,  the  orater 


was  emptied  to  the  depth  of  700  or  800  feet ;  its  rim  was  broken  on  the  south  and 
sunk  several  hundred  feet ;  and  the  lava,  deeply  sunk  in  the  chimney,  had  almost 
disappeared  from  sight.  Only  a  few  jets  of  vapor  and  gases,  called  fumaroles,  es- 
caped from  fissures  in  the  walls  and  at  the  bottom  of  the  crater. 

Gradually  the  fumaroles  become  more  numerous,  and  their  united  vapors  form  a 
column  constantly  ascending  from  the  crater.  The  lava  reappears  in  the  chimney, 
and  on  its  surface  there  is  formed  a  crust  which,  bursting  under  the  pressure  of 
imprisoned  steam,  sends  fragments  of  red-hot  lava  into  the  air.  These  falling  back 
accumulate  around  the  mouth  of  the  chimney,  and  build  up  a  cone  of  erup- 
limi  within  the  crater  of  the  main  volcanic  cone,  as  Vesuvius  proper  within  the 
crater  of  the  old  Monte  Somma.  A  smaller  cone  of  this  description  could  be 
seen  within  the  crater  of  Vesuvius  in  1828. 

This  cone  grows  constantly  in  dimensions,  occasional  overflows  of  lava  and  the 
materials  which  fall  from  the  crumbling  walls  of  the  crater  contributing  to  its  in- 
crease, until  the  crater  is  full  to  the  brim,  or  the  cone  of  eruption  rises  even  higher, 
as  was  the  case  in  1 756.     When  the  cra- 
ter is  thus  full  and  its  mouth  choked  up, 
the  expansive  forces  below  rapidly  ac- 
cumulate, and  soon  there  are  indications 
of  an  approaching  eruption. 

3.  Premonitions  of  an  Eruption. 
In  Vesuvius  among  the  indications  of 
the  approach  of  a  great  eruption  is  the 
drying  up  of  the  wells  and  springs, 
probably  due  to  the  increasing  heat  of 
the  ground,  causing  internal  evaporar 
tion,  and  to  the  formation  of  numerous 
fissures  in  which  the  underground  wa- 
ters disappear.  Loud  subterranean 
noises  like  the  reports  of  distant  artil- 
lery, shocks  of  earthquake  which  shake 
the  neighborhood  of  the  volcano,  and  a 
large  increase  of  the  volume  of  vapors 
which  escape  from  the  boiling  lava  im- 
prisoned in  the  chimney,  indicate  the 
struggle  going  on  within  the  mountain. 

4.  The  eruption  begins  generally 
with  a  tremendous  explosion  which 
seems  to  shake  the  mountain  to  its  very 
foundations,  and  hurls  into  the  air 
dense  clouds  of  vapor  and  ashes.  Other 
explosions  succeed  rapidly,  and  with 
increasing  violence,  each  sending  up  a 
white,  globular  cloud  of  steam,  or  aque- 
ous vapor.  This  long  array  of  clouds, 
accompanied  by  dark  ashes,  volcanic 
sand,  and  fragments  of  red-hot  lava  of 
all  sizes,  soon  forms  a  stupendous 
column. 

When  checked  in  its  ascending  mo- 
tion by  the  action  of  gravity,  the  col- 
umn expands  at  the  top,  its  form  resem- 
bling an  immense  umbrella,  or  the  Italian  pine,  to  which  it  has  often  been  com- 
pared. In  the  eruption  of  1822,  remarkable  for  its  violence  and  the  abundance 
of  ashes,  the  height  of  the  umbrella  was  estimated  at  7,000  feet,  and  in  that  of 
1779,  at  10,000  feet. 

Finally  the  boiling  lava  overflows  the  rim  of  the  crater  and  descends  in  fiery 
torrents  down  the  slopes ;  or,  bursting  the  mountain  by  its  weight,  finds  a  vent 
through  some  fissure  far  below  the  summit.  After  the  expulsion  of  the  lava  the 
eruption  is  generally  near  its  end,  though  it  does  not  necessarily  terminate  at  once. 
Alternate  phases  of  outbursting  steam,  ashes,  and  lava,  may  continue  with  more 
or  less  violence  for  weeks  or  even  months. 

5.  Atmospheric  Phenomena.  The  sudden  condensation  of  the  enormous 
accumulation  of  hot  vapor  thrown  into  the  air  by  the  eruption,  gives  rise  to  strik- 
ing atmospheric  phenomena.  Vivid  flashes  of  lightning  start  from  all  parts  of 
the  column,  and  play  about  the  clouds  above  ;  and  often  a  local  thunder-storm, 
formed  in  the  midst  of  a  clear  sky,  pours  a  heavy  rain  of  warm  water  and  ashes 
upon  the  slopes  of  the  mountain.  The  hot,  destructive  mud  torrents,  created  by 
these  rains,  have  often  been  mistaken  for  lava  streams. 

The  majesty  of  the  spectacle  is  still  greater  at  night.  Though  flames  of  burn- 
ing gases  are  of  rare  occurrence,  the  clouds  and  column  of  vapor  are  strongly  illu- 


VESUTIUS  IN  ERUPTION, 


minated  by  the  reflection  of  the  white-hot  lava  within  the  crater ;  and  fragments 
of  this  lava  constantly  thrown  into  the  air  give  the  column  all  the  brilliancy  of  a 
gigantic  piece  of  fire-work.  The  sky  itself,  far  and  wide,  partakes  of  the  same 
vivid  coloring  and  the  whole  scene  resembles  a  vast  conflagration. 

6.  Periods  of  Eruption.  A  series  of  eruptions,  separated  by  intervals  of 
but  few  years  during  which  indications  of  activity  are  still  numerous,  constitutes 
a,  period  of  eruption.  The  history  of  Vesuvius  shows  a  number  of  such  periods 
separated  by  centuries  of  almost  absolute  repose,  in  which  the  volcano  seemed  to  be 
extinct. 

At  the  birth  of  Christ,  Vesuvius  was  described  by  the  Roman  geographer, 
Strabo,  as  a  burnt  mountain,  but  it  had  never  been  known  to  show  any  activity. 
Its  crater,  nearly  full,  was  covered  with  a  dense  forest, and  its  slopes  adorned  with 
cultivated  fields,  villages  and  cities. 

In  the  year  63  several  shocks  of  earthquake  startled  the  inhabitants  of  its  de- 
lightful slopes,  and  sixteen  years  later,  in  79  a.  d.,  the  first  eruption  occurred,  af- 
ter which  the  northern  half  of  the 
mountain  alone  remained.  The  south- 
ern half  was  ground  to  powder,  and  the 
rain  of  hot,  wet  ashes  was  so  abundant 
as  to  cover  the  whole  neighborhood 
with  a  deep  layer  of  volcanic  materials, 
burying  the  flourishing  cities  of  Hercu- 
laneum  and  Pompeii,  which  have  been 
recently  exhumed  from  beneath  several 
yards'  depth  of  volcanic  tufa.  No  lava, 
however,  is  mentioned  in  the  descrip- 
tions of  this  eruption. 

From  that  time  to  the  year  lo.ii; 
only  seven  eruptions  are  recorded,  and 
lava  streams  are  noticed  for  the  first 
,time.  After  two  others,  occurring  in 
1049  and  1138,  the  mountain  entered 
into  a  period  of  repose  which,  inter- 
rupted only  by  slight  eruptions  in  1306 
and  1500,  lasted  nearly  500  years. 

In  1631,  when  the  volcano  had  been 
SO  long  dormant  that  its  slopes  were 
cultivated  to  the  foot  of  the  cone  of 
eruption,  and  the  walls  of  the  crater 
covered  with  forests,  an  eruption  took 
place  surpassing  in  destructiveness  all 
others  on  record. 

The  umbrella  shaped  mass  of  vapors 
and  ashes  extended  above  the  clouds 
and,  spreading  in  every  direction,  cov- 
ered a  large  extent  of  country  with  a 
thick  layer  of  volcanic  materials,  de- 
stroying all  vegetation.  The  rain  of 
ashes  extended  eastward  even  beyond 
the  Adriatic  Sea.  Torrents  of  hot  mud, 
an  1  seven  streams  of  fiery  lava,  flowing 
with  unusual  rapidity  down  the  moun- 
tain slopes  to  the  sea,  completed  the  work  of  destruction.  The  eruption  continued 
nearly  three  months,  and  a  number  of  beautiful  cities  and  villages  were  almost  or 
entirely  destroyed. 

This  great  eruption  was  followed  by  a  rest  of  thirty  years  ;  but  from  1660  to 
the  present  time,  eruptions  have  occurred  at  intervals  not  exceeding  ten  years. 
That  of  1794  was  the  most  imposing  and  destructive  which  has  occurred  since 
1631.  The  recent  eruption  of  1872  is  described  as  remarkable  both  for  the  immense 
quantity  of  lava  ejtcted  and  the  exceeding  brilliancy  of  the  spectacle  presented. 

7.  Some  important  contrasts  to  Vesuvius  are  presented  by  other  noted 
volcanoes,  occasioned  probably  by  differences  in  height  and  in  the  size  of  the  cra- 
ter. 

In  Stromboli,  a  volcano  less  than  3,000  feet  in  elevation,  situated  on  one  of  the 
Lipari  Islands,  the  eruptions  are  continuous  and  all  from  the  crater.  In  Vetumvs, 
4,000  feet  high,  the  eruptions  occur  at  irregular  intervals,  and  the  number  from 
the  crater  is  about  equal  to  that  from  fissures  in  the  sides. 

In  Etna,  a  volcano  nearly  11,000  feet  high,  situated  on  the  island  of  Sicily,  the 
eruptions  are  less  frequent  than  those  of  Vesuvius,  and  are  mainly  from  the  sides. 
It  seems  that  the  pressure  of  the  column  of  lava  in  the  lofty  chimney,  combined 


RESULTS   OF   INTERNAL   HEAT. —  VOLCANIC    PHENOMENA. 


15 


with  the  expansive  force  of  the  Imprisoned  vapors,  is  sufficient  to  burst  its  walls 
and  cause  deep  fissures  through  which  both  liquid  lava  and  ashes  escape.  The 
great  cone  is  studded  with  more  than  200  smaller  or  parasitic  cones,  formed  by  the 
lateral  eruptions  and  arranged  mainly  on  straight  lines  radiating  from  the  great 
crater. 

The  inference  is,  therefore,  that  the  lower  the  volcano  the  more  easy  and  frequent 
are  irs  eruptions,  and  the  greater  the  proportion  from  the  top ;  the  higher  the  vol- 
cano and  the  inclosed  column  of  lava,  the  greater  is  the  pressure  on  the  walls  of 
the  chimney,  the  more  frequent  the  bursting  of  the  mountain  and  the  lateral  erup- 
tions, and  the  more  numerous  are  the  parasitic  cones. 

The  volcanoes  of  the  Andes  form  an  apparent  exception  to  this  law.  Many  of 
them  have  an  altitude  of  more  than  20,000  feet,  yet  the  eruptions  are  wholly 
from  the  top.  This  is  accounted  for  by  the  fact  that  the  volcanic  peaks  rest  upon 
a  vast  and  elevated  mountain  system  which  is  too  massive  to  be  rent  by  the  inter- 
nal pressure.  The  inclosed  column  of  lava,  unable  to  reach  the  elevated  crater, 
is  tn>  rd  about  in  the  chimney  and  escapes  in  the  form  of  ashes  and  coarser  frag- 
ments, but  scarcely  ever  in  a  fluid  condition. 

The  volcanoes  of  the  Sandwich  Islands,  remarkable  for  their  exceedingly  flattened 
form  and  the  vast  size  of  their  craters,  are  distinguished  by  the  absence  of  ashes 
and  the  usually  quiet  flow  of  their  lavas  from  the  crater.  Extensive  lateral  erup- 
tions are,  however,  frequent  in  Mauna  Loa. 


ANALYSIS  OF   SECTION  VIII. 

I.  Nature  and  Formation  of  Volcanoes. 

1.  Volcano  Described. 

2.  Volcanic  Cone. 

a.  Mode  of  formation. 

b.  Evidences  of  this  formation. 

c.  Effect  of  formation. 
8.  Form  of  Volcanic  Cones. 

a.  Governed  by  what. 

(  Volcanoes  of  Sandwich  Islauds. 


b.  Examples. 


Vesuvius  and  Etna. 
Volcanoes  of  Andes. 
Volcanoes  of  Iceland. 


Volcanic  Products. 

a.  Ashes. 

b.  Sand. 

c.  Lava  fragments. 


d.   Lava  stream 


(  Appearance. 


|  Process  of  cooling. 
6.  Ejected  Matter. 

a.  Relative  amount  of. 

[  Hawaii. 

b.  Examples.  \  Iceland. 

{  Jorullo. 

6.  Number  op  Volcanoes. 

Active.    Extinct.     Position. 

7.  Height  op  Volcanoes. 

H.  Volcanic  Activity. 

a.  Activity  how  varying. 

b.  Typical  volcano. 

c.  How  volcanoes  differ. 

d.  In  what  respects  similar. 

TTI.  Vesuvius. 

1.  Position  and  Form.    Why  two  Summits. 

2.  State  op  Repose. 

a.  Early  condition  after  1822. 

b.  Later  condition. 


c.   Cone  of  eruption. 


How  formed. 
Size  attained. 


3.  Premonitions  op  Eruption. 

a.  By  wells  and  springs. 

b.  Noises. 

c.  Earthquakes. 

4.  Eruption. 

a.  Ejection  of  vapors  and  solid  matter. 

Description.     Amount. 

b.  Ejection  of  liquid  lava. 

c.  Subsequent  conditions. 

6.  Atmospheric  Phenomena  accompanying  Eruptions. 

a.  Observed  by  day. 

b.  Observed  by  night. 
6.  Periods  op  Eruption. 

a.  What  constitutes  a  period. 

b.  Examples  in  history. 

<•.   Kesults  of  eruption  in  79  A.  D. 

d.  Results  of  eruption  of  1631. 

e.  Condition  since  1631. 


7.  Contrasts  to  Vesuvius. 

a.  Contrasts  due  to  what. 

b.  Eruptions  of  Stromboli. 

c.  Eruptions  of  Vesuvius. 

d.  Eruptions  of  Etna. 
«.  Inference  drawn. 


f.  Apparent  exception. 


Where  occurring. 
How  explained. 


IX.  — RESULTS  OF  INTERNAL  HEAT  {Continued-). 

I.  Relative  Positions  of  Volcanoes. 

1.  Lines  of  Volcanoes.  Volcanoes,  though  they  are  but  local 
and  apparently  independent  accumulations  of  materials,  ordinarily 
occur  in  lines  more  or  less  irregular. 

The  six  volcanoes  of  Mexico,  among  which  Orizaba  and  Popocatepetl  are  the 
greatest,  are  on  a  line  which,  when  prolonged  into  the  Pacific,  strikes  the  vol- 
canic island  of  Socorro.  The  volcanoes  of  South  America  are  all  on  the  line  of 
the  Andes;  and  those  of  North  America  on  the  line  of  the  Sierra  Nevada  and 
Cascade  Mountains.  Numerous  examples  are  also  found  in  other  quarters  of  the 
globe. 

An  apparent  exception  to  this  rule  is  seen  where  volcanoes  seem 
isolated,  or  form  groups  consisting  of  a  central  volcano  surrounded 
by  secondary  cones.  But  even  in  this  case  the  linear  arrangement  is 
apparent,  since  the  groups  themselves  form  long  bands,  as  in  the 
Polynesian  islands  ;  and  in  the  larger  groups  the  disposition  of  the 
individual  volcanoes  in  parallel  lines  is  obvious,  as  in  Iceland  and 
the  Sandwich  Islands. 

2.  General  Distribution  op  Volcanoes.  Nearly  all  the  vol- 
canoes on  the  Earth's  surface  are  situated  along  the  mountain  ran- 
ges and  belts  of  islands  which  skirt  the  shores  of  the  continents, 
while  the  interior  is  almost  destitute  of  them.  Omitting  a  few 
extinct  craters,  the  only  well  authenticated  exception  to  this  rule  is 
found  in  the  few  volcanoes  around  the  Thian-Shan  Mountains,  in 
the  heart  of  the  great  Asiatic  continent,  nearly  2,000  miles  from 
the  sea. 


II.  Volcanic  Zones. 

1.  Two  great  terrestrial  zones  include  nearly  all  the  known 
volcanoes  of  the  globe,  arranged  in  long  bands  or  series,  or  in  isolated 
groups. 

The  first  zone  includes  the  vast  array  of  mountain  chains,  penin- 
sulas, and  bands  of  islands  which  encircle  the  Pacific  Ocean  with  a 
belt  of  burning  mountains.  Within  it  occur,  in  the  New  World,  (1) 
the  Andes  Mountains,  with  three  of  the  most  remarkable  series  of 
volcanoes — those  of  Chili,  Bolivia,  and  Ecuador —  separated  by  hun- 
dreds of  miles  ;  (2)  the  volcanic  group  of  Central  America ;  (3)  the 
series  of  Mexico ;  (4)  the  series  of  the  Sierra  Nevada  and  Cascade 
Mountains  ;  (5)  the  group  of  Alaska ;  and  (6)  the  long  series  of  the 
Aleutian  Islands. 

In  the  Old  World  are  (1)  the  series  of  Kamchatka  and  the  Kurile 
Islands  ;  (2)  the  group  of  Japan ;  (3)  the  series  south  of  Japan,  in- 
cluding Formosa,  the  Philippine  and  the  Molucca  Islands ;  and  (4) 
the  Australian  series,  including  New  Guinea,  New  Britain,  New  He- 
brides, and  New  Zealai/1.  In  this  vast  zone  there  are  not  less  than 
400  volcanoes,  170  of  which  are  still  active. 

The  second  zone,  though  less  continuous,  is  hardly  less  remarkable. 
It  is  the  belt  of  broken  lands  and  inland  seas,  which,  extending  round 
the  globe,  separates  the  northern  from  the  southern  continents,  and 
intersects  the  first  zone,  in  the  equatorial  regions,  nearly  at  right 
angles. 


RESULTS   OF   INTERNAL   HEAT.  — VOLCANIC   PHENOMENA. 


This  zone  includes  (1)  the  volcanic  regions  of  Central  America  and 
Mexico,  and  the  series  of  the  Lesser  Antilles  ;  (2)  the  groups  of  the 
Azores  and  Canary  Islands ;  (3)  the  Mediterranean  ifilands  and  penin- 
sulas, including  all  the  active  volcanoes  of  Europe ;  (4)  Asia  Minor 
with  numerous  extinct  volcanoes  ;  (5)  the  shores  of  the  Red  Sea  and 
Persian  Gulf,  and  the  two  Indias,  rich  in  traces  of  volcanic  action ; 
(6)  the  East  Indian  Archipelago  with  hundreds  of  burning  moun- 
tains ;  and  (7)  the  Friendly  Islands  and  other  volcanic  groups  of  the 
central  Pacific. 

In  this  zone  there  are  no  less  than  160  volcanoes,  so  that  the  two 
volcanic  zones  together  contain  560,  or  five  sixths  of  all  known. 

The  volcanic  forces  display  the  greatest  intensity  at  the  intersections  of  the  two 
volcanic  zones,  in  Central  America  and  the  East  Indian  Archipelago,  nearly  one 
third  of  all  known  volcanoes  occurring  in  these  two  regions.  Central  America, 
Mexico  and  the  Antilles  include  85  volcanoes,  while  the  East  Indian  Archipelago 
possesses  117. 

The  volcanoes  not  included  in  these  two  great  zones  are  isolated,  in  the  midst  of 
the  oceans,  or  .in  the  broken  polar  lands.  The  most  noted  are  the  Sandwich  Island 
group,  in  the  Pacific  ;  Bourbon  and  Mauritius,  in  the  Indian  Ocean ;  Cape  Verd 
Islands,  Ascension,  St.  Helena,  and  Tristan  da  Cunha,  in  the  Atlantic  ;  Iceland 
and  Jan  Mayen,  in  the  Arctic  Ocean  ;  and  Erebus  and  Terror,  in  the  Antarctic. 


III.  Causes  of  Volcanic  Action. 

1.  The  peculiar  distribution  of  volcanoes  suggests  the  nature 
and  causes  of  volcanic  action,  which  must  not  be  confounded  Avith 
that  more  general  force  which  has  uplifted  the  continents  and  de- 
pressed the  basins  of  the  oceans. 

Three  facts  are  obvious  and  significant,  namely:  (1.)  Nearly  all 
volcanoes  are  either  along  the  highest  border  of  the  continents,  or  in 
the  great  central  zone  of  fracture.  (2.)  Most  of  the  volcanic  groups 
exhibit  a  linear  arrangement.  (3.)  The  agent  at  work  in  these  mighty 
engines  is  mainly  vapor  of*  water,  or  steam  power. 

2.  The  primary  source  of  volcanic  action  is  the  heated  condi- 
tion of  the  Earth's  interior,  of  which  we  have  evidence  so  conclusive. 
The  effect  of  this  condition  will  necessarily  be  most  intense  along  the 
deep  fissures  which  establish  a  ready  communication  between  the 
interior  and  the  surface  of  the  globe. 

Nowhere  are  the  Earth's  strata  more  deeply  broken  than  on  the 
very  edge  of  the  continents ;  and  it  is  along  the  mighty  chasms 
caused  by  the  upheaval  of  these  vast  land  masses,  that  mountain 
chains,  such  as  encircle  the  sunken  basin  of  the  Pacific,  have  been 
raised.  There,  also,  volcanic  vents  abound  in  long  lines,  following 
either  the  top  or  the  foot  of  the  mountain  chains.  Similar  condi- 
tions exist  in  the  zone  of  fracture. 

The  folding  and  breaking  up  of  the  solid  crust  of  the  Earth,  and 
the  formation  of  those  great  surface  features  which  adorn  it,  must 
not  be  ascribed  to  the  heat  of  the  interior  mass,  but  to  its  slow  cool- 
ing and  the  consequent  contraction  of  its  bulk. 

Volcanic  action,  therefore,  is  not  the  cause  but  a  consequence  of 
the  upheaval  of  mountain  chains  and  continents ;  and  the  proximity 
of  volcanoes  to  the  sea  does  not  imply  the  necessity  of  sea  water  to 
their  formation,  but  is  due  to  the  deep  fissures  in  the  Earth's  crust, 
along  the  line  of  contact  of  the  depressed  ocean  basin  and  the  up- 
lifted continent. 

The  rain  water  which,  having  entered  the  ground,  instead  of  reappearing  in  the 
form  of  springs  or  artesian  wells,  penetrates  deep  into  these  subterranean  cavities, 
may  become  so  heated,  under  the  high  pressure  to  which  it  is  subject,  as  to  pro- 
duce the  usual  volcanic  phenomena. 


X.— 


ANALYSIS   OF   SECTION  IX. 

I.  Relative  Position  of  Volcanoes. 

1.  Lines  op  Volcanoes. 

a.  Ordinary  arrangement. 

b.  Examples. 

c.  Apparent  exception. 

2.  General  Distribution. 

a.  Ordinary  situation. 

b.  Exceptions. 

II.  Volcanic  Zones. 

a.  Number  of  zones. 

b.  Pacific  zone     Volcanic  regions  included. 

c.  Transverse  zone      Volcanic  regions  included 

d.  Greatest  intensity  of  volcanic  forces. 

e.  Volcanoes  not  included  in  zones. 

III.  Volcanic  Action. 

1.  Nature  and  Causes  — how  suggested. 

Prominent  facts  of  distribution. 

2.  Primary  Source  op  Volcanic  Action. 

a.  Effects,  where  most  intense. 

b    Strata,  where  most  deeply  broken. 

c.  Folding  of  Earth's  crust  ascribed  to  what. 

d.  Volcanic  action,  how  related  to  upheaval  of  mountain  chain. 


RESULTS   OF   INTERNAL   HEAT.     {Continued.) 

EARTHQUAKES. 


I.  Earthquake  Defined. 

1.  Earthquakes  are  movements  of  the  Earth's  crust,  varying  in 
intensity  from  a  hardly  perceptible  vibration  to  violent  convulsions, 
which  change  the  face  of  the  ground  and  overthrow  the  mosv  sub- 
stantial works  of  man. 

2.  Example.     The  earthquake  at  Lisbon,  Portugal,  on  the  morning  of  November 

I,  1755,  one  of  the  most  appalling  in  its  results,  exhibits  the  nature  of  these  commo- 
tions of  the  Earth's  crust,  and  the  phenomena  attending  them.  The  day  was  the 
festival  of  All-Saints,  and  the  churches  of  the  city  were  full  to  overflowing; 
when,  at  forty  minutes  past  nine,  a  rumbling  noise  was  heard  like  distant  thunder, 
gradually  increasing  until  it  resembled  the  sound  of  heavy  artillery.  A  faint 
shock  was  followed  by  a  heavier  one,  and  within  six  minutes  30,000  persons  were 
buried  under  the  ruins  of  the  churches  and  other  edifices ;  and  30,000  more  perished 
before  the  end  of  the  catastrophe. 

The  ground  seemed  to  undulate  like  the  waves  of  the  sea,  the  surrounding 
mountains  were  seen  rocking  violently  on  their  base,  and  broad  chasms  opened 
in  the  earth  and  closed  again.  More  than  3,000  persons  had  taken  refuge  from 
the  falling  edifices  on  a  broad  marble  quay  just  built  on  the  banks  of  the  Tagus, 
when  the  sea,  which  had  before  receded,  came  back  in  a  furious  wave  forty  feel 
high  and  swallowed  up  the  entire  multitude ;  then  rushing  upon  the  city  it  continued 
the  work  of  devastation.  Similar  oscillations  of  the  sea  were  repeated  several 
times;  and  when  the  commotion  ceased  several  hundred  feet  of  water  covered 
the  spot  which  the  quay  had  occupied. 

Fires,  kindled  in  the  fallen  dwellings,  spread  over  the  scene  of  desolation,  creat- 
ing a  vast  conflagration  which  completed  the  work  of  destruction.  The  ground 
continued  to  be  agitated  for  several  weeks  afterwards,  and  another  severe  shock 
occurred  in  December  following. 

One  of  the  most  remarkable  features  of  this  earthquake  was  the  extent  of 
country  over  which  it  was  felt.  All  western  Europe  was  agitated  ;  the  northern 
coast  of  Africa  suffered  considerably;  nearly  all  the  cities  of  Marocco  were  de- 
stroyed, and  fissures  whence  streams  of  water  issued,  were  opened  in  many  places. 
On  some  of  the  West  India  Islands  the  sea  rose  twenty  feet,  and  a  similar  rise  was 
observed  in  the  harbors  of  New  York  and  Boston.  The  entire  surface  disturbed  by 
this  earthquake  amounts,  according  to  Humboldt,  to  four  times  the  area  of  Europe. 

II.  Kinds  of  Earthquake  Movement. 

Three  kinds  of  motion  are  observed  in  earthquakes. 

1.  The  wave-like  or  undulatory  motion  is  most  common  and 
least  destructive.  It  appears  to  be  the  normal  one,  and  it  is  pos- 
sible that  the  others  may  be  simply  the  result  of  various  systems  of 
waves  intersecting  one  another.     The  waves  either  advance  in  one 


RESULTS   OF   INTERNAL   HEAT.  —  EARTHQUAKES. 


17 


direction,  like  waves  of  the  sea,  or  spread  from  a  central  point,  like 
ripples  produced  by  dropping  a  pebble  into  still  water. 

The  earthquakes  of  the  Andes  are  chiefly  linear,  being  propa- 
gated along  the  mountains,  with  the  undulations  perpendicular  to 
the  direction  of  the  ranges.  The  earthquake  at  Lisbon,  described 
above,  was  a  central  one,  the  concentric  waves  gradually  diminish- 
ing in  intensity  with  increasing  distance  from  the  place  of  origin. 

2.  The  VERTICAL  motion  acts  from  beneath  like  the  explosion  of 
a  mine,  and  when  violent  nothing  can  resist  its  force.  The  earth- 
quake at  Calcutta,  in  September,  1828,  owed  its  great  destructive- 
ness  to  the  fact  that  the  main  shock  was  vertical ;  and  one  in  Murcia, 
Spain,  in  1829,  destroyed  or  injured  more  than  3,500  houses. 

3.  The  rotary  or  whirling  motion,  is  the  most  dangerous,  but 
happily  the  rarest  of  all.  In  the  gr.eat  earthquake  of  Jamaica,  in 
1692,  the  surface  of  the  ground  was  so  disturbed  that  fields  changed 
places,  or  were  found  twisted  into  each  other. 

4.  The  velocity  with  which  the  earthquake  wave  moves  is  vari- 
able.      Humboldt 

estimates  the  ave-    ft 
rage  rate  at  from    j 
twenty-three  to    \ 
thirty-two  miles    ] 
per  minute. 


III.    Duration   of 
Earthquakes. 

Great  earth- 
quakes usually 
consist  of  a  series 
of  successive 
shocks,  some  of 
which  are  of  ex- 
traordinary v  i  o  - 
lence.  They  may 
be  repeated  at 
longer  or  shorter 
intervals,  during  a 
period  of  several 
days  and  weeks,  or 
even  of  several  months  and  years,  before  the  earthquake  is  at  an 
end. 

During  the  earthquake  on  the  coast  of  Venezuela,  which  began 
on  the  21st  of  October,  1766,  and  destroyed  the  city  of  Cumana 
in '  a  few  minutes,  the  earth  continued  to  be  shaken  almost  every 
hour  for  a  period  of  fourteen  months.  After  the  destruction  of  the 
beautiful  city  of  Messina,  on  the  island  of  Sicily,  in  1783,  the 
ground  continued  to  be  agitated  almost  daily  for  ten  years. 


IV.  Distribution  of  Earthquakes. 

1.  General  pacts  :  —  (1.)  No  part  of  the  globe  is  absolutely  free 
from  earthquakes. 

(2.)  There  are  circumscribed  regions  in  which  the  surface  is  liable 
to  be  shaken  simultaneously,  such  a  region  being  called  an  earth- 
quake area. 

(3.)  The  most  extensive  earthquake  areas,  and  those  in  which  the 
convulsions  are  most  numerous  and  violent,  are  situated  within  the 
two  great  volcanic  zones  —  that  is,  the  coast  regions  of  the  Pacific 


EARTHQUAKE  AT  LISBON. 


Ocean,  and  the  transverse  zone  separating  the  northern  from  the 
southern  continents. 

2.  Th»  analogy  IN  THE  distribution  of  earthquakes  and  volca- 
noes is  evident,  yet  the  former  occupy  a  far  more  extensive  domain 
than  the  latter.  Both  are  most  intense  in  their  action  along  the 
great  fractures  of  the  Earth's  crust ;  yet  we  are  not,  on  that  account, 
to  conclude  that  the  one  is  the  cause  of  the  other  ;  they  only  require 
similar  conditions  for  their  manifestation. 

The  immediate  connection  of  earthquakes  with,  volcanic  eruptions  is  evident  in 
many  instances,  yet  these  are  of  a  special  kind.  Volcanic  eruptions  often  take 
place  without  earthquakes,  as  in  the  Sandwich  Islands  ;  and  many  severe  earth- 
quakes occur  in  regions  far  removedljfrpm  any  active  volcano,  and  destitute  of 
volcanic  rocks.  Even  in  volcanic  districts  the  most  extensive  earthquakes  bear 
apparently  no  relation  to  the  surrounding  volcanoes.  The  two  sets  of  phenomena 
may  have  a  common  cause,  but  they  must  not  be  confounded  or  considered 
as  necessarily  belonging  to  the  same  class. 

V.  Relation  to  Atmospheric  and  Astronomical  Conditions. 

Within  the  trop- 
ics, especially, 
earthquakes  are 
most  frequent  in 
that  part  of  the 
year  in  which  the 
greatest  atmos- 
pheric disturban- 
ces take  place. 
They  are  most 
dreaded  at  the  be- 
ginning  of  the 
rainy  season,  when 
the  monsoons1  are 
changing  their  di- 
rection. In  the 
Molucca  islands 
the  inhabitants,  at 
this  period,  for- 
sake their  houses 
for  greater  safety, 
and  shelter  them- 
selves under  tents 


or  the  lightest  bamboo  structures  until  the  danger  is  past. 

3.  Perrey,  by  comparing  7,000  observations,  found  the  number  of  earthquakes 
occurring  at  the  syzygies  —  when  the  attraction  of  the  Sun  and  Moon  is  com- 
bined and  the  Moon  is  nearest  the  Earth  —  greater  than  at  the  time  of  the  quad- 
ratures, when  the  Moon  is  most  distant ;  also  that,  during  an  earthquake,  the 
shocks  are  more  frequent  where  the  Moon  is  on  the  meridian.  Wolf  finds  a  co- 
incidence with  the  periodicity  of  the  Sun's  spots,  the  years  in  which  these  are  most 
numerous  being  those  in  which  earthquakes  are  most  frequent. 


VI.  Theory  of  Earthquakes. 

1.  A  General  Cause  Necessary.  No  satisfactory  explana- 
tion of  the  phenomenon  of  earthquakes  has  as  yet  been  proposed. 
Local  earthquakes,  preceding  or  accompanying  a  volcanic  eruption, 
are  doubtless  due  to  the  action  of  the  volcano ;  but  all  which  take 
place  outside  of  volcanic  districts,  and  especially  those  general  con- 
vulsions, disturbing  areas  hundreds  of  thousands  of  miles  in  extent, 
must  be  assigned  to  some  more  general  cause.  This  cause  may  possi- 
bly be  found  in  the  constantly  increasing  tension  produced  in  the 


i  See  page  78, 1. 


O     Longitude    20    East    from   40     Greenwich.  60 


E.  Sandoz.Sc  J . Krumholz ,  -del . 


Entered  according  toAct  of  Cona^ess  in  the  Year  1872 .  6, 


k    Ml  H 


E  xp  1  a  11  a  t  i  o  n  - 
Volcanoes    are   marked  by  black   dots.  (  •  ) 
and  the  Regions    visited  by  Earthquakes 
are  distinguished   by  shading,  which,  is  darker 
in  proportion    to   the    force   and   frequency 
of    the    shocks  . 

Coral  reefs    and    Islands    are   marked    by 
a  blue    shading  . 

In  the  Profiles   the  black  peaks    are    the 
Volcanoes,  and  the  limit 
is  indie  t  , „ ., , 


EARTHQUAKES 


JHlaja  T        i^Bro^      Ratter  |    L         ySh-to;  Pop.catepetl^ <fc $*%$&* 


S*EHh«       M*  FairweaUnr         M?S!  Helens 
T         ;M?Brown 

t f ^T7    , 

Hal 


&£. 


l.^gecumbe 


TdlilllM 

**S. Salvador       ,  . 
I      Irasu,   ,Ch»nqui 


Deception  l£ 

'  ,      '         I  PichilU'ka 

Sui.il'- 
Purace  j  ♦]  An  lis  ana 

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N     OjR      T      ii  \,  A     M      V. 


fyf  twt  to 

no 

I«T<(«1-    L 

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1 

tH ,  *    — i.'.tjl.". 

_' 

i  Co.  in  the  Office  of  the  Librarian  c? Congress .  Washington .  C.T. . 


tiC&  A.&  Johnston  ,  Edinburgh  and 


20 


RESULTS   OF  INTERNAL   HEAT.  —  EARTHQUAKES. 


Earth's  strata,  by  the  steady  cooling  and  contraction  of  the  heated 
mass  inclosed  by  the  hardened  outer  crust.  In  this  case  every  dif- 
ference of  pressure  upon  the  Earth's  crust,  whether  arising  from 
atmospheric  or  astronomical  causes,  may  have  a  share  in  the  pro- 
duction of  earthquakes. 


ANALYSIS  OF   SECTION  X. 

I.  Earthquake  Phenomena  Described. 

1.  General  Definition. 

2.  Earthquake  op  Lisbon  Inscribed. 

a.  Time  and  effects.    . 

b.  Movement*  of  ground. 

c.  Movements  of  sea. 

d-  Extent  of  area  agitated. 

II.  Kinds  of  Motion. 

1.  Undulatory  Movement. 

a.  Character,  and  relation  to  other  motions. 

b.  Directions  of  waves. 

c.  Examples.     Linear.    Central. 

2.  Vertical  Movement.    Example. 
8.  Rotary  Movement.    Example. 
4.  Velocity  op  Earthquake  Wave 

III.  Duration  of  Earthquakes. 

1.  General  Statement. 

2.  Examples. 

IV.  Distribution  of  Earthquakes. 

1.  General  Facts  Observed. 

a.  Extent  of  phenomenon. 

b.  Earthquake  areas. 

c.  Earthquake  zones. 

2.  Analogy  of  Distribution  with  that  op  Volcanoes. 

Connection  of  earthquakes  with  volcanic  action 

V.  Relation  to  Atmospheric  and  Astronomical  Cause. 

1.  Connection  with  Atmospheric  Disturbances. 

2.  What  Connection  with  Astronomical  Causes  Observe"). 

VI.  Theory  of  Earthquakes. 

1.  A  General  Cause  Necessary.    Why. 

Where  such  cause  possibly  found. 


QUESTIONS   ON  THE  MAP    OF  VOLCANOES   AND 
EARTHQUAKES. 

How  are  volcanoes  indicated  on  the  map?     (See  Explanation  in  right-hand  margin.) 

Bow  are  the  regions  which  are  subject  to  earthquakes  marked? 

Un  what  part  of  the  Earth's  surface  are  volcanoes  most  numerous? 

How  do  North  and  South  America  compare  in  regard  to  the  number  of  their  volcanoes  ? 

What  are  the  principal  volcanic  groups  of  South  America  ? 

In  which  are  volcanoes  most  numerous  ? 

What  great  volcanic  groups  between  South  America  and  the  main  mass  of  North  America  ? 

What  two  groups  on  the  Pacific  coast  north  of  the  Tropic  of  Cancer? 

What  are  the  principal  volcanic  peaks  in  the  Cascade  group  ? 

What  group  of  volcanoes  between  North  America  and  Asia? 

Name  the  principal  volcanic  groups  of  Eastern  Asia? 

Where  are  most  of  these  volcanoes  situated  ? 

In  what  direction  does  the  Philippine  chain  of  volcanoes  extend? 

In  what  direction  does  the  chain  of  the  Sunda  Islands  extend? 

How  do  this  chain  and  the  Philippine  compare  in  direction  at  their  intersection? 

What  short  chain  east  of,  and  parallel  to,  the  Philippine  chain  ? 

What  group  in  the  midst  of  the  Pacific,  in  nearly  the  same  latitude  ? 

What  celebrated  volcano  in  the  Sandwich  Islands  ? 

Hew  does  the  long  volcanic  chain  extending  from  New  Guinea  to  New  Zealand,  compare  in 
direction  with  the  adjacent  Australian  coast? 

In  what  part  of  this  chain  arc  volcanoes  most  numerous? 

What  solitary  volcano  in  the  eastern  part  of  the  Pacific  Ocean,  near  the  tropic  of  Capricorn  ? 

What  islands  containing  volcanoes,  form  a  long  chain  extending  from  Easter  Island  to  the 
volcanic  group  of  New  Guinea? 

How  docs  this  long  volcanic  chain  compare  in  direction  with  the  southern  coasts  of  Asia  and 
Europe  ? 

What  volcanoes  in  the  northeastern  part  of  the  Indian  Ocean  ? 

In  the  southwestern  part? 

What  noted  volcanoes  in  the  Mediterranean  regions? 

What  one  in  Western  Asia  ? 

In  what  part  of  Africa  is  a  prominent  volcanic  region ?    In  what  part  of  Asia? 


What  volcanic  islands  in  the  north  of  Africa  ? 
What  volcanic  islands  in  the  middle  Atlantic,  west  of  Africa? 

In  what  portions  of   the  New  World  are  earthquakes  most  frequent  and  violent  ?     In  what 
portions  of  Europe'  and  Asia  ?    In  what  Asiatic  islands  ? 
What  islands  in  the  South  Pacific  subject  to  frequent  earthquakes?    In  the  Central  Pacific? 


REVIEW  OF  PART  I. 

Note. — The  pages  to  which  the  questions  refer  are  indicated  by  figures  in  the  margin. 

(Page  1.)  What  forms  the  subject  of  geographical  science? 

From  what  points  of  view  may  the  Earth  be  studied  geographically? 

What  are  the  resulting  divisions  of  the  science  ? 

(2.)  How  many  are  the  modes  of  treatment  in  the  geography  of  nature? 

What  are  some  of  the  more  important  problems  investigated  in  physical  geography  ? 

How  does  physical  geography  differ  from  geology  ? 

Enumerate  the  topics  discussed  in  Section  I.,  and  the  primary  divisions  of  each,  as  shewn  in 
the  tabular  analysis. 

How  is  the  Earth  related  to  the  Sun  and  other  heavenly  bodies? 

(3.)  What  is  the  comparative  importance  of  the  Earth  among  the  heavenly  bodies? 

What  bodies  compose  the  solar  system  ? 

Enumerate  the  topics  discussed  in  Section  II.,  and  state,  briefly,  the  substance  of  each. 

How  are  the  primary  planets  grouped  ? 

How  do  the  two  groups  compare  in  size?     In  density?     In  distance  from  the  Sun? 

To  which  group  does  the  Earth  belong  ? 

What  motion  is  common  to  the  Sun  and  all  the  planets  ? 

What  other  motion  have  all  the  planets  ? 

(5.)  How  does  the  velocity  of  revolution  vary  in  the  different  planets? 

The  velocity  of  rotation  ? 

The  time  of  revolution  ? 

What  is  the  position  of  the  axes  of  the  planets  in  respect  to  the  planes  of  their  orbits? 

What  is  the  effect  of  the  inclination  of  the  axis  of  a  planet  ? 

How  does  the  Earth  compare  with  the  other  planets  in  its  various  physical  conditions  ? 

Enumerate  the  topics  discussed  in  Section  III.,  and  the  subdivisions,  both  primary  and  sec- 
ondary, of  each. 

(6. )  What  is  the  form  of  the  Earth  ? 

The  approximate  dimensions? 

The  specific  gravity  ? 

Enumerate  the  topics  discussed  in  Section  IV.,  and  give,  briefly,  the  substance  of  each. 

(7.)  How  do  the  degrees  of  longitude  compare  in  length  in  different  latitudes?     Why  ? 

Explain  the  relation  of  difference  of  longitude  to  difference  of  time. 

Enumerate  the  topics  discussed  in  Section  V.,  and  give  the  substance  of  each. 

(8.)  What  is  a  magnet?    What  properties  are  exhibited  by  all  magnets? 

What  property  of  a  magnet  is  exhibited  by  the  Earth  ? 

What  is  magnetic  declination  ;  and  where  is  there  no  variation  ? 

Enumerate  the  topics  discussed  in  Section  VI.,  and  the  primary  subdivisions  of  each. 

(10.)  What  evidences  are  there  of  a  high  temperature  within  the  Earth? 

(11.)  How  do  thermal  springs  give  evidence  of  internal  heat? 

Where  are  the  most  remarkable  geyser  regions  ? 

Explain  (See  page  10,)  the  formation  of  the  geyser. 

How  are  artesian  wells  supposed  to  be  formed? 

(12.)  State  the  results  of  observations,  in  wells  and  mines,  on  the  Earth's  temperature. 

Describe  a  volcanic  mountain,  and  the  mode  of  its  formation. 

Enumerate  the  topics  discussed  in  Section  VII.,  and  give  the  substance  of  each. 

(13. )  On  what  does  the  shape  of  a  volcanic  cone  depend  ? 

What  are  the  chief  substances  ejected  by  volcanoes  ? 

What  can  you  say  of  the  amount  of  materials  ejected? 

How  does  the  activity  of  volcanoes  vary  at  different  times  ? 

Describe  Vesuvius  during  a  period  of  repose. 

(14.)  What  are  the  usual  premonitions  of  an  eruption?    Describe  an  eruption. 

What  atmospheric  phenomena  accompany  a  violent  eruption  ? 

When  was  the  first  eruption  of  Vesuvius  in  historic  time,  and  what  its  result  ? 

What  contrasts  to  Vesuvius  are  presented  by  other  famous  volcanoes? 

Enumerate  the  topics  discussed  in  Section  VIII.,  and  the  primary  subdivisions  of  each. 

( 15. )  Describe  the  general  distribution  of  volcanoes. 

Where  are  the  two  great  volcanic  zones  situated  ? 

What  are  the  principal  groups  in  the  Pacific  zone  ? 

In  the  transverse  central  zone  ? 

(16.)  What  is  the  primary  source  of  volcanic  action? 

Enumerate  the  topics  discussed  in  Section  IX.,  and  give  the  substance  of  each. 

How  is  volcanic  action  related  to  the  upheaval  of  mountain  chains  ? 

What  are  earthquakes? 

Describe  the  great  earthquake  at  Lisbon. 

What  are  the  different  classes  of  earthquake  movement  ?    How  do  they  compare  in  violence  ? 

(17.)  With  what  velocity  does  the  earthquake  wave  move? 

How  are  ihe  most  extensive  earthquake  areas  situated? 

What  coincidence  with  atmospheric  disturbances  has  been  observed? 

What  general  cause  may  be  supposed  to  give  rise  to  earthquakes? 

Enumerate  the  topics  discussed  in  Section  X.,  and  give  the  substance  of  each. 


PART    II. 


THE    LANDS. 


I. —  GENERAL  ARRANGEMENT  OF   LAND    MASSES. 


.  Geographical  Elements  of  the  Earth. 

The  solid  land,  the  liquid  sea,  and  their  common  gaseous  emrel- 
>pe,  the  atmosphere,  mutually  acting  upon  one  another,  form  the 
hree  great  geographical  elements  which,  under  the  influence  of  the 
>un,  support  life  in  all  its  varied  forms. 

The  extent,  form,  and  relative  position  of  the  land  masses,  materi- 
ully  modify  climate,  and  regulate  the  distribution  and  development 
>f  organic  life.  Hence  the 
ht<ly  of  these  fundamental 
eatures  of  the  globe,  though 
(pparently  elementary,  is  of 
>rimary  importance. 

The  proportion   of   land  to 

rater    upon    the   globe    is    as 

IE  :  72,  the  land  covering  53,- 

©0,000  square  miles,  the  sea 

44.000,000. 

I.  The  Land  Masses. 

1.  Division.  The  land  is 
either  concentrated  into  one 
ast  mass,  nor  uniformly  dis- 
ributed  over  the  globe. 

It  consists  of  six  great  bodies 
ullcd  continents,  widely  differ- 
lg  in  size  and  form  ;  and  a 
niltitude  of  small  fragments 
died  islands,  which  skirt  the 
lores  of  the  continents  or  dot 
te  broad  expanse  of  the  sea. 


from  which  there  results,  in  each,  a  belt  of  broken  lands  —  peninsulas 
and  islands.  Within  this  belt  are  the  great  archipelagoes  of  the  East 
and  West  Indies,  and  the  peninsulas  of  southern  Asia  and  Europe. 

These  regions  form  part  of  a  broad  transverse  zone  which  may 
properly  be  designated  the  central  zone  of  fracture.  Its  position  can 
be  traced  by  describing  a  circumference  upon  the  globe,  from  Behring 
Strait  as  a  centre,  with  a  meridian  arc  of  80°  as  a  radius. 

Figure  1  exhibits  the  divergent  arrangement  of  the  land  masses,  and  the  zone 
of  fracture.  The  latter  passes  over  the  Caribbean  Sea,  in  the  New  World  ;  and 
the  Mediterranean  Sea  and  East  Indian  Archipelago,  in  the  Old. 


III.    Grand 
trasts. 


Terrestrial  Con- 


This   division  of    the    land 
lto  diverse  bodies  produces  a  diversity  of  climate,  and  promotes  a 
tiler  and  more  perfect  development  of  every  order  of  life. 

2.  Position  on  the  Globe.  The  land  masses  are  crowded 
kether  around  the  north  pole,  their  northern  limits  being  about 
te  70th  parallel.  Thence  they  extend  towards  the  south,  in  three 
ast  divergent  tracts,  terminating  in  points  widely  separated  one 
•om  another,  and  very  distant  from  the  south   pole. 

The  sea  encircles  the  south  pole,  and  sends  three  great  arms  north- 
'ard,  between  the  divergent  land  masses,  forming  the  Pacific,  the 
itlantic,  and  the  Indian  Ocean. 

8.  ZONE  of  Fracture.  Each  of  the  three  divergent  tracts  of 
md  is  invaded  nearly  midway  by  the  ocean,  or  by  great  inland  seas, 


1.  Northern  and  South- 
ern Worlds.  The  trans- 
verse zone  of  fracture  divides 
each  of  the  divergent  tracts  of 
land  into  two  continental  mas- 
ses, or  a  pair  of  continents. 
Hence  there  are  three  northern 
and  three  southern  continents, 
forming  two  groups  which  pre- 
sent marked  contrasts. 

The  northern  continents  lie 
near  together,  and  almost  whol- 
ly within  temperate  latitudes ; 
the  southern  continents,  on  the 
contrary,  ara  isolated  one  from 
another,  and  lie  chiefly  in  trop- 
ical latitudes. 

2.  Eastern  and  Western 
Worlds.  Two  of  the  three  di- 
vergent pairs  of  continents  are  crowded  together  upon  one  side  of 
the  globe,  while  the  third  is  isolated  upon  the  opposite  side  ;  the 
eastern,  or  Old  World,  thus  contains  more  than  twice  as  much  land 
as  the  western  or  New  World. 

This  difference  in  area,  together  with  the  concentration  of  the 
lands  in  the  former,  and  their  greater  separation  in  the  latter,  con- 
stitutes a  second  terrestrial  contrast  of  great  importance,  whose 
influence  is  felt,  through  climate,  upon  every  order  of  life. 

3.  Continental  and  Oceanic  Worlds.  A  third  great  con- 
trast is  produced  by  the  combined  concentration  of  the  lands  upon 
the  northern  and  eastern  regions  of  the  globe.  This  gives  rise 
to  a  northeastern  or  Land  Hemisphere,  and  a  southwestern  or  Wa- 


FIG   1.      DIVERGENCE  OF  LAND    MASSES,   AND    ZONE   OF   FRACTURE. 


22 


HORIZONTAL   FORMS    OF   THE   CONTINENTS. 


tir  Hemisphere,  first  traced  by  Carl  Ritter,  and  properly  designated 
the  Continental  and  Oceanic  Worlds. 

The  former  contains  over  six  sevenths  of  the  land  surface  of  the 
globe.  The  latter  includes  only  Australia  and  the  southern  extremi- 
ties of  Asia  and  South  America, 
which,  with  numerous  islands, 
make  less  than  one  seventh  of 
the  solid  surface  of  the  Earth. 

IV.  Relative  Areas  and  Position 
of  Laud  Masses. 

The  western  pair  of  conti- 
nents is  the  longest ;  and  the 
two  Americas  are  nearly  of  the 
same  size.  Europe-Africa  is 
the  shortest  pair,  and  the 
smaller  continent  is  at  the 
north,  the  larger  at  the  south. 
In  Asia-Australia  the  larger  is 
at  the  north,  the  smaller  at 
the  south.  Thus  the  greatest  variety  is  obtained,  both  in  size  and 
in  relative  situation,  by  the  slanting  direction  of  the  zone  of  fracture. 
The  relative  areas  of  the  three  pairs  of  continents,  as  well  as  that  of  the  conti- 
nents individually,  is  represented  to  the  eye  by  Figure  3.  The  numbers  within 
the  several  rectangular  spaces  give  the  areas  of  the  continents  in  square  miles. 

ANALYSIS   OF  SECTION   I. 

I.  Geographical  Elements. 

a.  Elements  enumerated. 

b.  Importance  of  the  arrangement  of  land  masses. 

c.  Proportion  of  laud  and  water  on  globe. 
II.  The  Land  Masses. 

1.  Division  op  Land. 

a.  Extent  of  division. 

b.  Importance  of  division. 

2.  Position  op  Lands  on  Globe. 

a.  Northward  position  of  land  masses. 

b.  Converse  position  of  sea. 

3.  Central  Zone  of  Fracture. 

a.  Kelation  to  diverging  lands. 

b.  Position  of  zone. 

III.  Terrestrial  Contrasts. 

1.  Northern  and  Southern  Worlds. 

a.  Number  and  arrangement  of  continents. 

b.  Position  of  northern  group. 

c.  Position  of  southern  group. 

2.  Eastern  and  Western  Worlds. 

a.  Relative  position  of  pairs  of  continents. 

b.  Relative  extent  of  Old  and  New  World. 

c-  Results  of  difference  in  area  and  compactness. 
8   Continental  and  Oceanic  Worlds. 

a.  Basis  of  third  series  of  contrasts. 

b.  Relative  amount  of  land  in  each  hemisphere. 

IV.  Areas  of  Continents. 

a.  Relative  areas  and  positions. 

b.  Absolute  areas  in  English  square  miles. 

II.  — HORIZONTAL  FORMS  OF  THE  CONTINENTS. 


I.  Twofold  Aspect  of  Continen- 
tal Forms. 

Every  continent  presents  it- 
self to  the  observer  in  a  two- 
fold aspect  —  as  a  surface,  with 
peculiarities  of  horizontal  form 
and  outline,  given  by  the  line 
of  contact  of  land  and  water  ; 
and  as  a  solid,  with  peculiari- 
ties of  vertical  form,  given  by 
the  elevation  of  its  surface 
above  the   level   of    the   sea. 


FIG.   2.      LAND   AND    WATER   HEMISPHERES 


EUROPE. 

NORTH  AMERICA. 
8,261,000. 

3,565,200. 

ASIA. 

AFRICA. 
11,314,300. 

16,216,600. 

80UTH   AMERICA. 

8,889,500. 

AUSTRALIA. 

2,948,300. 

FIG.    3.       RELATIVE    AREAS    OF    THE     CONTINENTS. 


The  former,  though  the  more  obvious,  is  not  the  fundamental  char- 
acter, since  it  is  the  result  of  the  latter. 

II.  General  Figure  of  Continents. 

1.  Common  Fundamental 
Figuee.  Every  great  conti- 
nental mass  has  a  figure  more 
or  less  triangular.  The  two 
Americas  are  each  triangular ; 
the  double  continent,  Asia- 
Europe,  forms  a  triangle  ;  and 
the  main  body  of  Africa  has  a 
similar  figure. 

Australia  alone  approaches  a 
quadrilateral  form ;  and  even 
this,  including  the  island  of 
Tasmania,  which  is  properly  a 
part  of  the  continental  figure, 
approximates  to  a  triangular 
outline.  This  remarkable  coincidence  in  the  fundamental  form 
of  the  continents,  evidently  indicates  a  common  law  of  structure, 
which  it  is  the  province  of  geology  to  discover. 

2.  Direction  op  Greatest  Prolongation.  In  the  two  Amer- 
icas, the  sharpest  angle  of  the  continental  figure  is  turned  towards 
the  south,  and  the  greatest  elongation  is  in  the  direction  of  the  me- 
ridians. 

In  Asia-Europe,  on  the  contrary,  the  sharpest  angle  is  towards 
the  west,  and  the  greatest  elongation  of  the  double  continent  is  in 
the  direction  of  the  parallels.  In  Africa  and  Australia,  while  the 
continents  narrow  towards  the  south,  their  greatest  extent  from  east 
to  west  is  approximately  equal  to  that  from  north  to  south. 

The  difference  in  the  direction  of  elongation  in  America  and  Asia- 
Europe,  causes  marked  differences  in  other  respects.  The  former, 
extending  over  9,000  miles  from  north  to  south,  traverses  all  tin- 
climatic  zones,  exhibiting,  as  a  result,  great  variety  in  the  character 
of  its  plants  and  animals.  Asia-Europe,  having  a  length  of  i 
7,000  miles,  has,  from  the  Pacific  shores  to  the  Atlantic,  a  general 
similarity  of  climate,  vegetation,  and  animals. 

III.  Continental  Outlines. 

1.  Differences  in  Outline.  The  outlines  of  the  continents 
display  striking  differences.  Some  are  deeply  indented  with  gulfs 
and  inland  seas,  or  have  projecting  peninsulas ;  while  others  pre- 
sent a  massive  form  with  simpler  outlines,  without  indentations  or 
projections  worthy  of  notice. 

2.  Importance  of  Articu- 
lation of  Coasts.  These 
irregularities,  or  articulations 
of  outline,  are  of  vast  impor- 
tance to  the  civilization  of  the 
continent. 


They  greatly  increase  the 
length  of  the  coast  line,  and 
the  contact  of  land  and  water  ;. 
they  favor  the  formation  of  con- 
venient harbors,  and  open  the 
interior  of  the  continents  to 
commerce   by  sea,  facilitating 


HORIZONTAL  FORMS    OF   THE   CONTINENTS. 


23 


BTTB.OPE. 
19,800. 


3,565,200 
Sq.  miles 

ASIA. 
85,500. 

16,216,600 

Sq.  miles. 

' 

AFRICA. 
16,200. 


11,314,300 
Sq.  miles. 

AUSTBALIA. 
8,760. 


8,948,800 

Sq.  niiks. 


communication  with  other  parts  of  the  world  ;  and  the  sea,  penetrat- 
ing into  the  land,  moderates  the  extremes  of  temperature,  and  in- 
creases the  moisture  of  the  atmosphere,  and  the  fertility. 

Again,  the  subdivision  of  the  continents  into  peninsulas,  form- 
ing diverse  physical  regions, 
gpcurea  a  higher  development 
of  human  society  by  assisting 
in  the  formation  of  distinct 
nationalities  ;  like  those  cre- 
ated in  the  great  peninsulas  of 
India  and  Arabia,  Greece, 
Italy,  and  Spain. 

It  is  a  remarkable  fact  that  the 
deeply  indented,  well  articulated 
continents,  are,  and  have  always 
been, the  abode  of  the  most  highly 
civilized  nations.  The  unindented 
(uus,  shut  up  within  themselves  and 
less  accessible  from  without,  have 
played  no  important  part  in  the 
drama  of  history.  It  should  be  re- 
membered, however,  that  variety  of 
contours  is  but  the  expression  of  a 
complicated  inner  structure,  which, 
together  with  the  climatic  situation 
of  the  northern  continents,  has  had 
a  large  share  in  this  result. 

3.  Gradation  in  Artic- 
i  i.ation.  A  significant 
gradation  is  exhibited  by  the 
several  continents  in  regard  to 
irregularities  of  outline. 

Europe  surpasses  all  the  others  in  the  relative  magnitude  of 
its  indentations  find  projections;  the  proportion  of  its  penin- 
sulas to  its  entire  area  being  as  1  :  4.  Three  great  peninsulas 
—  the  Hellenic  peninsula,  Italy,  and  Spain — project  into  the  Medi- 
terranean ;  while  Bretagne,  Denmark,  and  Scandinavia  enrich  the 
shores  of  the  Atlantic.  Even  the  British  Isles  are  scarcely  more  than 
a  projection  of  the  continent.     (See  page  38,  British  Isles.~) 

Asia  is  second  in  the  relative  extent  of  its  peninsulas,  the  pro- 
jecting lands  being  to  the  entire  area  of  the  continent  as  1  :  5.5. 
Asia  Minor  on  the  west,  Arabia,  India,  and  Indo-China  on  the  south, 
and  China,  Manchuria  with  Corea,  and  Kamchatka,  advancing  into 
the  waters  of  the  Pacific,  form  a  wide  border  of  projecting  lands,  con- 
taining the  richest  regions  of  the  continent. 

North  America,  though  considerably  less  indented,  still  has  penin- 
sulas bearing  to  its  entire  area  the  proportion  of  1  :  14.  Flor- 
ida, Nova  Scotia,  and  Labrador  are  the  most  prominent  on  the  At- 
lantic coast ;  Boothia  Felix  and  Melville  Peninsula  on  the  Arctic  ; 
and  California  Peninsula  and  Alaska  on  the  Pacific. 

The  southern  continents,  on  the  contrary,  are  nowhere  deeply 
penetrated  by  the  waters  of  the  ocean.  The  Gulf  of  Arica,  in 
South  America,  the  Gulf  of  Guinea,  in  Africa,  and  the  Great  Aus- 
tralian Bight,  are  merely  gentle  bends  in  the  coast  line.  The  slight 
projections  of  the  Atlas  Mountain  region  and  Somali  in  Africa,  and 
Fork  Peninsula  in  Australia,  are  scarcely  to  be  reckoned  among  true 
peninsulas. 

These  three  continents  are  aptly  styled  by  Ritter,  trunks  without  branches,  or 
bodies  without  members;  while  the,  three  northern  continents  are  beautiful  trees 
with  abundant  spreading  branches,  or  bodies  richly  articulated  with  useful  mem- 
bers. 

4.  The  Amount  of  Indentation  in  each  continent  is  shown  in  Figure  4. 
The  inner   squares    represent    the    area   of    the  continents,   and   their   contours 


show  the  length  of  coast  required   to   inclose  that  area  without   indentations  or 
projections. 

The  contours  of  the  outer  squares  represent,  on  the  same  scale,  the  actual 
length  of  coast  line  inclosing  the  same  area  as  it  exists  in  the  continents.  The 
difference  between  the  contours  of  the  outer  and  inner  squares,"  is  the  true  measure 

of  the  amount  of   indentation.     A 


NORTHERN   CONTINENTS. 


NOKTH  AMERICA. 
27,700. 


8,261,000 

Sq.  miles. 

glance  reveals  the  difference  be- 
tween the  northern  and  the  south- 
ern continents  in  this  respect. 

The  following  TABLE  gives 
the  length  of  the  coast  line 
in  each  continent,  and  the  area 
without  islands,  in  English 
miles. 


SOUTHERN   CONTINENTS. 


Europe, 

Asia, 

North  America, 

Africa, 

Australia, 

South  America, 


3,£65,200  sq.  m. 
1G,216  600     " 

8,261,010     " 
11,314,300     k* 

2,948,300     " 

6,889 ,50  J     " 


Length   of 

Co;i.-t. 


19,800  m. 
35,500  " 
27,700  " 
16,200  « 
8,760  " 
15.700  " 


SOUTH  AMERICA. 
16,700. 


FIG.    4.       LENGTH     OF    THE    COAST-LINK    IN    EACH    CONTINENT,    COMPARED    WITH    THE    LINE 
ENCLOSING  ITS  CONSOLIDATED  AREA. 


This  table  shows  that  Eu- 
rope has  3,600  miles  more  of 
coast  than  Africa,  though  the 
latter  has  more  than  three 
times  the  area  of  the  former. 
North  America,  but  little 
larger  than  South  America, 
has    12,000     miles    more    of 

coast.     Australia,  nearly  the  size  of  Europe,  has  less  than  half  its 

length  of  coast. 


ANALYSIS  OF   SECTION   II. 

I.  Twofold  Aspect  of  Continental  I  onus 

a.  Continent  as  a  surface 

b.  Continent  as  a  solid. 

c.  Relative  importance  of  the  two. 

II.  General  Figure  of  Continents. 

1.  Common  Fundamental  Figure. 

a.  Figure  belonging  to  alt  great  masses. 

b.  Examples. 

c.  Figure  of  Australia. 

d.  Inference  from  coincidence  in  fundamental  form. 

2.  Direction  of  Greatest  Elongation. 

a.  The  Americas. 

b.  Asia-Europe. 

c.  Africa  and  Australia. 

d.  Effect  of  difference  in  direction  of  elongation. 

III.  Continental  Outlines. 

1.  Differences  exhibited  by  Continents. 

2.  Importance  of  Irregularities. 

a.  Influence  on  extent  of  coast  and  communication. 
b    Influence  on  climate. 

c.  Influence  oo  development  of  society. 

d.  Coincidence  between  articulation  of  outlines  and  historical 

importance. 

3-  Gradation  of  Continents  in  Articulation  of  <\m-ts. 

;i.   Kurope. 

b.  Asia. 

c.  North  America. 

<1.  Southern  continents.     Figure  used  by  Ritter. 

i.  Amount  of  Indentation  of  Continents. 

a.  How  exhibited  by  diagram. 

b.  How  exhibited  by  table. 
o.  Comparison  of  coast  lines. 


24 


VERTICAL  FORMS  OF  THE  CONTINENTS. 


III.  — VERTICAL  FORMS  OF  CONTINENTS. 

I.  General  Relief  Forms. 

1.  Relief  Defined.  The  vertical  configuration  of  a  continent 
or  island  —  that  is,  its  elevation  as  a  whole,  varied  by  plains,  table- 
lands, mountains,  and  valleys  —  is  called  its  relief. 

The  elevation  of  any  given  point,  reckoned  from  the  level  of  the  sea 
as  a  common  base,  is  called  its  altitude.  The  height  of  a  hill,  moun- 
tain, or  plateau,above  the  surrounding  country,  is  its  relative  elevation. 

2.  Classes  of  Relief  Forms.  Although  the  forms  of  relief 
are  exceedingly  varied,  they  may  all  be  referred  to  two  great  classes, 
namely  :  elevations  in  mass,  and  linear  elevations. 

Elevations  in  mass,  or  great  areas  of  nearly  uniform  altitude,  are 
called  plains  or  lowlands,  when  their  altitude  is  less  than  1,000  feet ; 
and  plateaus  or  table-lands,  when  it  reaches  or  exceeds  1,000  feet. 

Linear  elevations  are  those  whose  breadth  is  slight  compared  with 
their  length.  In  this  class  are  included  chains  of  mountains  and 
hills,  and  the  intervening  valleys.  The  term  hills  is  applied  to 
ridges  less  than  2,000  feet  in  elevation. 

3.  Importance  of  a  Study  of  Relief  Forms.  The  loftiest 
mountains,  when  compared  with  the  diameter  of  the  Earth,  are  but 
as  grains  of  sand  upon  a  globe 

several  feet  in  diameter ;  yet  the 
element  of  altitude  so  powerfully 
affects  climate,  and  organic  life, 
that  a  knoAv ledge  of  the  reliefs  of 
the  several  continents  is  of  the 
utmost  importance. 

A  difference  in  altitude  of  no 
more  than  330  feet,  is  sufficient 
to  produce  a  difference  in  temper- 
ature of  1°  Fahrenheit,  being 
equivalent  to  a  difference  of  sev- 
enty miles  in  latitude.  An  in- 
crease in  altitude  of  but  a  few  thousand  feet,  therefore,  changes  en- 
tirely the  character  of  a  region,  like  a  removal  of  it  from  torrid  to 
temperate  latitudes,  or  from  temperate  to  frigid. 

Again,  the  relief  of  a  continent  controls  its  drainage,  shaping  the 
river  basins,  and  directing  the  course  of  its  flowing  waters  ;  and  in- 
fluences, to  a  certain  extent,  the  direction  and  character  of  the  winds, 
and  the  distribution  of  rain. 


II.  Plains. 

1.  Extent  of  Plains.  Plains  occupy  nearly  one  half  of  the 
surface  of  the  continents.  They  are  most  extensive  and  unbroken 
on  the  Arctic  slopes  of  the  Old  World,  and  in  the  interior  of  the 
two  Americas. 

The  great  Siberian  plain  extends  from  the  northeastern  extrem- 
ity of  Asia  to  the  Ural  Mountains  and  Caspian  Sea  ;  and  the  Euro- 
pean plain  stretches  from  the  Ural  westward,  through  Russia  and 
North  Germany,  to  the  lowlands  of  Holland. 

In  North  America  the  great  central  plain  extends,  with  but  slight 
interruptions,  from  the  Arctic  shores  to  the  Gulf  of  Mexico. 

In  South  America  the  plains  of  the  Orinoco  basin,  the  Selvas  of 
the  Amazon,  and  the  Pampas  of  the  La  Plata,  form  an  uninterrupted 
series  of  low  lands  which,  continued  by  the  plains  of  Patagonia  to 
the  southern  extremity  of  the  continent,  extend  over  a  distance  of 
3,500  miles  from  north  to  south. 

The  interior  of  Australia  is  also  a  plain  of  great   extent.     The 


KORTH  AMERICA. 
Highland. 

EUROPE.    Highland. 

ASIA. 
Highland. 

Lowland. 

AFRICA. 
Highland. 

Lowland. 

Lowland. 

S.  AMEMCA.    Highland. 

Lowland. 

Lowland. 

AUSTRALIA.    Lowland. 

FIG.    5.      RELATIVE   AREA   OF   HIGHLAND   AND    LOWLAND    IN   EACH   CONTINENT. 


plains  of  China,  Hindoostan,  and  the  Euphrates  basin,  in  Asia,  justly 
celebrated  as  the  seats  of  mighty  civilized  nations,  are  smaller  and  of 
a  more  local  character. 

2.  Surface.  On  account  of  differences  in  the  character  of  their 
surface,  plains  may  be  divided  into  three  general  classes,  namely  : 
alluvial,  marine,  and  undulating  plains. 

Alluvial  plains  are  almost  absolutely  level,  their  surface  often 
being  unbroken  by  any  elevation  deserving  even  the  name  of  a  hill. 
They  are  formed  of  materials  deposited  by  rivers  upon  overflowed 
lands  along  their  courses,  or  in  shallow  waters  about  their  mouths, 
the  deposits  gradually  converting  the  shallows  into  flat  moist  lands. 
The  most  marked  examples  of  alluvial  plains  are  the  delta  of  the 
Mississippi  and  the  flat  bottom  land,  from  thirty  to  eighty  miles  in 
width,  lying  between  its  bluffs;  the  great  plains  of  the  Amazon, 
the  Orinoco,  and  the  La  Plata;  the  low  plains  of  China,  Hindoostan, 
and  the  lower  Euphrates  ;  the  delta  and  valley  of  the  Nile ;  and  the 
plains  of  the  Po  and  of  the  lower  Rhine. 

Marine  plainsare&o  called  because  they  seem  to  have  been  formed 
under  sea  water,  and  resemble  the  sandy  bottom  of  an  ancient  ocean. 
Theyshow  but  slight  inequalities  of  surface,  due  to  local  accumula- 
tions of  sand  drifted  by  the  currents,  or  to  other  accidental  causes  ; 

and  where  there  is  a  scarcity  of 
rain  the  soil  is  frequently  im- 
pregnated with  salt,  soda,  and 
other  substances  remaining  alter 
the  evaporation  of  sea  water. 

Plains  of  this  class  are  situated, 
chiefly,  on  the  shores  of  the  con- 
tinents, or  around  great  salt  hikes 
and  inland  seas  ;  like  the  sandy 
plains  of  our  Atlantic  slope,  and 
those  adjacent  to  the  Baltic,  the 
Caspian,  and  the  Aral  Sea. 

Undulating  plainx  have  the 
surface  varied  by  swells  of  greater  or  less  elevation,  but  rarely  much 
above  the  general  level.  They  occupy  an  intermediate  position  be- 
tween the  highlands  of  the  continents  and  the  low  alluvial  and  ma- 
rine plains. 

Of  this  class  are  the  larger  part  of  the  plains  in  the  Mississippi 
basin,  and  the  uplands  at  the  eastern  foot  of  the  Appalachian  Moun- 
tains ;  the  central  and  southern  plains  of  Russia,  and  the  eastern 
half  of  the  Siberian  plain. 

3.  The  productiveness  and  general  aspect  of  plains  varies  as 
widely  as  their  surface. 

Treeless  plains,  whose  vegetation  consists  of  grasses  and  other  her- 
baceous plants,  or  stunted  shrubs,  occur  in  every  continent,  and  are 
designated  by  a  variety  of  terms. 

In  ^North  America  the  fertile  treeless  plains  are  termed  "prairie*  " 
(meadows),  while  the  sterile  ones,  east  of  the  Rocky  Mountains,  are 
known  as  "  the  plains." 

In  South  America  the  Spanish  term  "llano"  (plain),  and  the 
Peruvian  "  pampa,"  designate  the  treeless  plains  of  the  Orinoco 
and  La  Plata  basins.  Those  of  eastern  Euro])e  and  Asia  are  denom- 
inated "  steppes  ;  "  while  more  limited  treeless  regions  in  western 
Europe  are  called  "  landes  "  and  "heaths." 

Wherever  treeless  plains  are  subject  to  periodical  rains,  they  lose 
their  verdure  in  the  season  of  drought,  and  assume  the  aspect  of  a 
desert ;  but  they  resume  their  freshness  on  the  return  of  the  rain,  and 
many  are  adorned  with  a  great  variety  of  beautiful  flowers. 


VERTICAL   FORMS    OF   THE   CONTINENTS. 


25 


The  marine  plains  being  chiefly  sandy,  are  the  least  fertile ;  but  the 
more  favored  ones  produce  forests  of  pine  and  excellent  pasturage ; 
like  the  Baltic  plains  of  Europe,  and  the  sandy  plains  on  the  Atlan- 
tic coast  of  North  America. 

The  plains  of  the  Caspian  Sea  and  western  Siberia  are  dreary 
steppes,  covered  with  coarse  grasses,  often  growing  in  tufts,  alter- 
nating with  patches  of  heather,  furze,  dwarf  birch,  and  other 
stunted  shrubs ;  or  old  sea  bottom,  covered  with  salt  efflorescence. 
Immense  reaches  of  flat  country,  near  the  Arctic  shores  of  Asia 
and  Europe,  consist  of  frozen  marshes,  called  tundras,  where  mosses 
and  lichens  are  almost  the  only  vegetation. 

The  undulating  plains  produce  the  most  extensive  forests  of  tem- 
.perate  latitudes  ;  but  where  subject  to  long  summer  droughts,  — as 
in  the  western  half  of  the  Mississippi    basin,  in  southern  Russia, 
and  in  many  other  localities,  —  these  plains  are  often  treeless. 

The  alluvial  plains  are  among  the  most  valuable  portions  of  the 
globe.  There  the  waters,  descending  the  slopes  of  the  continents, 
meet,  bringing  with  them  the  spoils  of  the  upland,  and  accumulating 
that  rich  soil  upon  which,  in  all  periods  of  history,  men  have  gathered 
by  millions. 

On  the  alluvial  plains  of  the  Old  World  civilization  began  and 
developed ;  and  their  inexhaustible  fertility  supplied  the  wants  of 
the  most  populous  nations  of  antiquity.  The  great  centres  of  an- 
cient civilization  in  Egypt,  China,  India,  and  Babylonia,  all  had 
their  growth  in  alluvial  plains,  built  up  and  fertilized  by  the  mighty 
rivers  which  traverse  those  countries. 

In  the  New  World  are  the  cane  fields  and  forests  of  the  lower  Mis- 
sissippi ;  the  Llanos  of  the  Orinoco,  during  one  half  of  the  year  cov- 
ered by  the  richest  pasturage,  bright  with  flowers,  but  during  the 
other  half  a  parched  waste ;  the  Selvas  of  the  Amazon,  a  luxuriant 
forest  covering  more  than  a  million  square  miles ;  and  the  treeless 
Pampas,  with  their  tall  grasses  and  thickets  of  clover  and  thistles  : 
all  illustrating  the  endless  richness  and  variety  of  nature. 

4.  Altitude.  Alluvial  and  marine  plains  generally  have  but  a 
slight  altitude,  while  the  undulating  plains  are  sometimes  consider- 
ably elevated.  The  Mississippi  valley,  at  St.  Louis,  1000  miles  from 
the  ocean,  is  hardly  400  feet  above  the  sea  level ;  and  the  Amazon,  at 
an  equal  distance  from  the  sea,  does  not  reach  250  feet.  The  marine 
plains  adjacent  to  the  Caspian  and  Aral  Seas  are  still  lower,  the 
larger  portion  being  below  the  sea  level. 

5.  The  area  covered  by  low  lands  in  eacli  continent  is  shown,  approximately, 
in  the  following  table,  which  gives  their  extent  in  English  square  miles,  and  their 
proportion  to  the  entire  area  of    the  continent. 


A^ia, 

Europe, 

North  America, 


Area  of  Lowlands. 


7,116,000  sq.  miles. 
2,541,000         " 
3,840,000         " 


Propor- 
tion. 


Africa, 

South  America, 

Australia, 


Area  of  Lowlands. 


1,000,000  sq.  miles. 
5,417,000         " 
2,500,000         " 


Propor- 
tion. 


ANALYSIS   OF   SECTION   III. 

I.  General  Relief  Forms. 

1    Relief  Defined. 

Relief  distinguished  from  altitude. 

2.  Classes  op  Relief  Forms. 

a.  Elevations  in  mass. 

Plains.     Plateaus. 

b.  Linear  elevations. 

Mountains.     Hills. 

3.  Importance  op  Study  op  Reliefs. 

a.  Greatest  elevations  compared  with  diameter  of  Earth. 

b.  Effect  of  elevation  on  climate. 

c.  Effect  of  relief  on  drainage  of  continent?. 


II.  Plains. 


1.  Extent  op  Plains. 

a.  Proportion  to  entire  area  of  continents. 

b.  Geographical  position  of  great  plains. 

c.  Examples. 

Siberian  Plain. 
European  Plain. 
Plains  of  North  America. 
Plains  of  South  America. 
Plains  of  Australia. 

d.  Less  extensive  plains. 

2.  Surface  of  Plains. 

a.  Alluvial  plains. 

Surface. 

Formation. 

Examples  of  alluvial  plains. 

b.  Marine  plains. 

Their  nature. 
Surface  and  soil. 
Geographical  situation. 
Examples. 

c.  Undulating  plains. 

Surface. 
Examples. 

3  Productiveness  op  Plains. 

a.  Treeless  plains  how  designated. 

In  North  America. 

In  South  America. 

In  Eastern  Europe  and  Asia. 

In  Western  Europe. 

Treeless  plains  under  periodical  rains. 
Q.  Marine  plains. 

c.  Undulating  plains. 

General  character. 
Exceptional  regions. 

d.  Alluvial  Plains. 

General  Character. 

Alluvial  plains  of  Old  World. 

Alluvial  plains  of  New  World. 

4  Altitude  of  Plains. 

a.  Altitude  of  different  classes. 

b.  Examples. 
6.  Area  of  Plains. 


IV.— VERTICAL   FORMS    OF    THE    CONTINENTS    Con- 
tinued'). 
I.  Plateaus. 

1.  Plateaus  are  situated  either  between  two  lofty  mountain 
chains,  which  form  their  margins,  or  descend  by  successive  terraces  to 
the  nearest  seas ;  or  they  pass,  by  insensible  gradations,  from  the 
base  of  high  mountains  to  the  low  plains  in  the  interior  of  the  conti- 
nents. 

The  Great  American  Basin,  between  the  Rocky  and  Sierra  Ne- 
vada Mountains,  and  the  plateau  of  Thibet,  between  the  Hima- 
laya and  Kuenlun  Mountains,  are  examples  of  the  first  position ;  and 
the  table-land  of  Mexico,  of  the  second.  The  third  is  seen  in  the 
high  plains  at,  the  eastern  foot  of  the  Rocky  Mountains,  which  de- 
scend from  an  altitude  of  5,000  or  6,000  feet,  at  the  foot  of  the 
mountains,  to  the  low  plains  in  the  centre  of  the  Mississippi  basin. 

2.  The  surface  of  plateaus  varies  as  widely  as  that  of  plains, 
some,  like  the  Great  American  Basin,  being  even  quite  mountainous; 
but  in  all  cases  the  lowest  part  of  the  plateau  has  still  a  considerable 
elevation. 

Although  in  the  sloping  plateaus,  such  as  the  one  east  of  the 
Rocky  Mountains,  there  may  be  no  well  defined  limit  at  which  the 
name  of  plateau  must  be  exchanged  for  that  of  plain,  yet  striking 
differences  in  climate,  as  well  as  in  vegetable  and  animal  life,  dis- 
tinguish the  plateaus  in  general  as  one  of  the  most  strongly  marked 
geographical  forms. 

3.  Elevation  of  Plateaus.  The  plateaus  most  remarkable 
for  their  elevation  are,  —  Thibet,  from  10,000  to  18,000  feet  above 
the  sea ;  and  the  elongated  valley-like  highlands,  from  10,000  to 
13,000  feet  high,  between  the  two  chains  of  the  Andes,  in  South 


America.  These,  with  some  smaller  regions,  also  situated  between 
lofty  mountain  ranges,  may  be  denominated  plateaus  of  the  first  order. 
Plateaus  of  the  second  order,  averaging  from  4,000  to  8,000  feet, 
are  the  most  extensive.  East  Turkestan  and  Mongolia,  in  central 
Asia  ;  the  plateau  of  Iran,  in  western  Asia ;  Abyssinia,  and  the  vast 
plateau  which  occupies  all  the  southern  part  of  Africa  ;  and  the  broad 
table-land    which 

m 

fills  the  western  half 
of  North  America 
with  a  continuous 
mass  of  high  land  : 
are  examples  of  this 
order. 

Plateaus  of  the 
third  order,  from 
1,000  to  4,000  feet 
in  altitude,  occupy 
the  gre^t  peninsu- 
las ;  as  the  Deccan, 
Arabia,  Asia-Mi- 
nor, and  Spain.  The 
central  plateau  of 
France,  and  those 
of  Switzerland,  Ba- 
varia, and  Transyl- 
vania, are  oi  the 
same  order. 

4.  Importance 
of  Plateaus  . 
Great  plateaus  of 
the  first  and  second 

orders,  together  with  their  accompanying  mountain  ranges,  form 
the  nucleus  or  back-bone  of  almost  every  continent ;  determining  its 
general  form,  and,  to  a  great  extent,  the  direction  and  combination 
of  its  water  courses. 

5.  The  nature  of  the  soil  and  climate  of  great  plateaus  is  in  gene- 
ral such  as  to  render  them  the  least  useful  portions  of  the  continents. 

Sahara  —  with  an  average  altitude  of  1,500  feet  —  and  the  higher 
plateaus  of  Mongolia,  Iran,  and  the  Great  American  Basin,  may 
serve  as  types. 

Their  surface  consists  of  hardened  sand   and  rock ;    of  hillocks 
and  plains  of   loose  sand  con- 
stantly shifting  by  the  wind;    upheaving  force. 
and  of  immense   tracts,  as   in 
Mongolia,  covered  with  pebbles 
varying  from  the  size  of  a  wal- 
nut, or  even  less,  to  a  foot  in 
diameter :  all  indicating  the  original  transporting,  grinding,  and  de- 
positing of  these  materials  by  water. 

Salt  lakes  without  outlet  occur  in  each,  and  salt  efflorescence  often 
covers  the  ground. 

A  lack  of  rain  to  wash  from  the  soil  substances  injurious  to 
vegetation,  and  furnish  the  water  necessary  for  the  growth  of  plants, 
leaves  these  plateaus  generally  sterile,  and  some  of  the  most  exten- 
sive are  in  part,  if  not  wholly,  deserts. 

II.  Mountains. 

1.  Appearance  of  Mountains.  Mountains  rise  in  long  and 
comparatively  narrow  lines  or  ridges,  the  tops  of  which  are  often 
deeply  indented,  presenting  to  the  eye  the  appearance  of  a  series  of 


THE  GREAT  WESTERN  PLATEAU  OF  NORTH  AMERICA,  NEAR  FOB     BBIDGER. 


FIG.  6.       MOUNTAINS    UY    FOLDING.      A  TRANSVERSE    SECTION  OF  THE   JURA. 


peaks  detached  one  from  another.  As  each  of  these  peaks  or  dis- 
tinct elevations  is  called  a  mountain  and  often  receives  a  sepai'ate 
name,  the  common  designation  chain  or  range  of  mountains  is  nat- 
urally applied  to  the  whole. 

2.  A  mountain  CHAIN  therefore,  is  not  a  series  of  isolated 
peaks  touching  each  other  only  at  the  base  ;  but  has  the   form  of  a 

prism  with  a  broad 
base  and  two  oppo- 
site slopes.  The 
upper  edge  of 
some  is  nearly  even 

—  as  in  the  Appa- 
lachian Mountains, 

—  of  others  deeply 
indented,  as  in  the 
Rocky  Mountains 
and  the  Alps. 

These   indenta- 
tions, even    in    ex- 
treme cases,  do  not 
extend   more    than 
half  way  to  the  base, 
leaving    the    lower 
part  of  the  mountain 
chain  an  unbroken 
or  continuous  mass. 
The   top   of  the 
ridge,    from   which 
the  waters  descend 
on    opposite    sides, 
is  called  the  crest; 
and  the  notches  between  the  peaks,  from  which  transverse  valleys 
often  stretch  like  deep  furrows  down  the   slopes  of  the  chain,  are 
called  passes. 

3.  Mountain  System.  Mountain  chains  are  seldom  isolated,  but 
are  usually  combined  into  systems,  consisting  of  several  more  or 
less  parallel  and  connected  chains,  with  their  intervening  vail 

—  as  the  Appalachian  system,  the  Alps,  and  the  Andes. 

These  systems  often  form  great  mountain  zones,  thousands  of 
miles  in  length  and  several  hundred  miles  broad  ;  hence  their  gene- 
ral slope  averages  but  few   degrees.     In  many  cases  one  side   of 

the  system  is  flanked  by  a  pla- 
teau descending  very  gradual- 
ly towards  the  distant  plains; 
while  on  the  other  side  an  ab- 
rupt descent  terminates  in  low 
plains  lying  at  the  base  of  the 
mountains.  This  formation  is  apparent  both  in  the  Alps  and  the 
Himalaya  Mountains. 

4.  Formation  of  Mountains.  Most  mountain  chains  seem  to 
have  been  produced  by  tremendous  lateral  pressure  in  portions  of 
the  Earth's  crust,  causing  either  long  folds,  or  deep  fissures  with 
upturned  edges  rising  into  high  ridges,  the  broken  strata  forming 
ragged  peaks. 

There  are,  accordingly,  two  distinct  types  of   mountain   chains 

—  mountains  by  folding,  which  are  generally  of  moderate  eleva- 
tion ;  and  mountains  by  fracture,  to  which  belong  the  highest  chains 
of  the  globe.  The  Appalachian  Mountains,  in  North  America,  and 
the  Jura,  in  Europe,  are  examples  of  the  first ;  the  Rocky  Moun- 
tains, Andes,  Alps,  and  Himalayas,  of  the  second.  (See  Figs.  6  and  7.) 


VERTICAL   FORMS    OF   THE   CONTINENTS. 


27 


5.  Mo  l.MNG  are  curved  into  long  arches,  either  en- 

tire or  broken  at  the  summit ;  forming  a  system  of  long,  parallel 
ridges,  c  al    height,  separated,   by  trough-like  valleys. 

The  crest*  of  the  ridges,  seen  against  the  horizon,  present  a  nearly 
uniform  outline,  with  neither  sharp  peaks  nor  deep  passes.  Here 
and  there,  however,  deep  gaps,  or  gorges,  cut  the  chains  trans- 
versely to  their  base,  allowing  the  rivers  to  escape  from  one  valley 
to  another. 


Direction  of 
upheaving  force. 


These  gaps  are  numerous  in  the  Appalachian  Mountains, 
entering  the  Atlantic  north  of  the 
Roanoke,  rise  in  or  beyond  the 
westernmost  range,  and  cross  the 
other  ranges  eastward  through  such 
breaks. 

South  of  the  Roanoke  similar  gaps 
permit  the  streams  rising  in  the  east- 
ernmost range  to  cross  the  system 
westward,  and  enter  the  Misssis- 
sippi. 


All  the  long  rivers 


TRANSVERSE  SECTION  OF  THE  CENTRAL  ALPS 

Mont  Blanc. 


Direction  of 
upheaving  force. 


FIG.    7.      CHAIN   OF   MOUNTAINS   BY    FRACTURE. 


6.  Mountains  by  Fracture.  In  systems  of  mountains  pro- 
duced by  fracture,  there  is  usually  one  main  central  chain,  with 
several  subordinate  ranges.  They  have,  however,  less  regularity 
and  similarity  among  themselves  than  the  parallel  chains  of  moun- 
tains by  folding. 

The  crests  are  deeply  indented,  cut  down  one  third  or  one  half  the 
height  of  the  range,  forming  isolated  peaks  and  passes  which  present 
to  the  eye  the  appearance  of  a  saw,  called  in  Spanish,  Sierra  ;  in  Por- 
tuguese, Serra.  Such  ranges  are  frequently  distinguished  by  these 
terms,  as  the  Sierra  Ne- 
vada, in  North  America ; 
and  the  Serra  do  Mar,  in 
Brazil. 


III.  Valleys. 

1.  Valleys  occur 
both  in  mountain  sys- 
tems and  in  the  more 
uniform  surface  of  pla- 
teaus and  plains. 

2.  Valleys    among 

MOUNTAIN    RANGES     Owe 

their  existence  primarily 
to  folds  or  fissures  in  the 
Earth's  crust,  produced  in 
the  upheaving  of  the  ran- 
ges ;  but  they  are  subse- 
quently deepened,  wid- 
ened, and  otherwise 
changed  in  form  and  ex- 
tent, by  the  action  of  rains 
and  frosts,  and  the  streams  to  which  they  furnish  a  pathway. 

Mountain  valleys  are  distinguished  as  longitudinal  and  transverse, 
the  former  lying  parallel  with,  and  the  latter  crossing,  the  ranges. 
In  mountains  by  folds  the  longitudinal  valleys  are  numerous  and  ex- 
tensive, the  transverse  comparatively  few. 

In  mountains  by  fracture,  though  the  main  valleys  are  longitudi- 
nal, the  transverse  valleys  are  the  most  numerous  and  strongly 
marked.  They  usuallv  consist  of  a  series  of  basins  between  the 
ranges,  connected  by  narrow  denies  or  clefts  with  precipitous  sides. 


THE    GREAT   CANON   AND   LOWER    FALLS   OF  THE  YELLOWSTONE, 


The  basins  become  successively  lower,  as  they  recede  from  the  origin 
of  the  valley,  the  connecting  defiles  usually  having  a  considerable 
slope.  Most  of  the  Alpine  lakes,  celebrated  for  their  picturesque 
beauty,  occupy  deep  basins  at  the  outlet  of  transverse  valleys. 

3.  Valleys  in  plains  and  plateaus  are  mainly,  if  not  entirely, 
the  result  of  the  erosion,  or  wear  of  the  surface,  by  running  water. 

Little  rills,  formed  by  the  rains  or  issuing  from  springs,  set  out  on 
their  course  down  the  slope  of  the  groimd,  each  wearing  its  small 
furrow  in  the  surface.     Uniting  they  form  a  rivulet  which  wears  a 

broader  and  deeper  channel ; 
and  the  rivulets  in  turn  com- 
bining, form  rivers  which  pro- 
duce still  greater  effects. 

Thus  the  entire  surface  of 
plains  is  furrowed  by  valleys 
descending  from  the  higher  to 
the  lower  levels.  In  the  lower 
course  of  the  screams  the  val- 
ley is  usually  wider  and  less  deep  than  in  the  upper. 

In  the  great  basin  of  the  Mississippi,  for  example,  is  one  grand 
central  valley,  cut  by  the  main  stream  in  the  line  of  lowest  level, 
towards  which  the  valleys  of  the  Missouri,  the  Arkansas,  the  Ohio, 
and  a  multitude  of  smaller  streams,  all  converge. 

The  central  valley,  in  the  upper  course  of  the  stream,  is  from  300  to  500  feet  deep, 
its  boundaries  consisting  of  abrupt  bluffs  from  whose  top  stretches  away  the  sur- 
rounding plain  ;  and  the  breadth  of  the  valley  does  not  much  exceed  that  of  the 
stream  in  time  of  high  water.  In  the  middle  course,  below  the  Missouri,  it  attains 
a  width  of  ten  miles,  while  the  height  of  the  bluffs,  or  more  properly  the  depth  of 

the  valley,  is  only  about  200 
feet.  Farther  down  the  stream 
the  valley  is  from  60  to  80 
miles  wide,  while  the  depth 
gradually  decreases.  (Seepage 
48,  Section  of  the  Mississippi 
Valley.) 

The  most  remarkable 
examples  of  valleys  by 
erosion  occur  in  the  pla- 
teaus adjacent  to  the 
Rocky  Mountains.  The 
Grand  Canon  of  the  Col- 
orado, 300  miles  long,  has 
a  depth  of  from  3,000  to 
6,000  feet  below  the  sur- 
rounding country.  The 
sides  of  this  tremendous 
gorge,  which  are  nearly 
or  quite  precipitous,  ex- 
hibit the  successive  geo- 
logical strata  down  to  the 
oldest  rocks.  A  similar 
formation  exists  in  the 
upper  course  of  the  Yellowstone,  one  of  the  main  tributaries  of  the 
Missouri,  and  to  a  less  extent  in  all  the  streams  flowing  through  the 
high  barren  plateaus. 

The  term  valley  is  frequently,  but  very  improperly,  applied  to  the  entire  basin  of 
a  river,  whence  great  misconceptions  result  in  discussing  the  character  and  forma- 
tion of  valleys.  Thus  the  basin  of  the  Mississippi, —  that  is,  the  entire  ana 
drained  by  the  stream,  stretching  from  the  Rocky  to  the  Appalachian  Mountains, 
—  is  frequently  called  the  "  great  Mississippi  Valley  ";  but  the  latter  term  prop- 
erly applies  only  to  the  depression  within  which  the  course  of  the  river  lies.  This 
was  excavated  by  running  water ;  but  the  basin,  or  the  great  trough  between  the 


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AMERICA       STATES 


I  11     U    ^  Peaks  Mexico  »■      VdelFuego 


TChihtialraa   '  CE\"E\L       Bogota         Quito  PLATEAU    of    BOLIVIA 

MEXICO      AMERICA    OOLfMBIA  PEKCB  OLIVIA       CHILI 


PATAGO.V1A 


ORLD 

PROJECTION. 


byAfiuyot . 


120    longitude        HO      last  from      160      Greenwich      180 


WScA.-K.Joh  nston.Edinhuroh  Se 


30 


VERTICAL  FORMS   OF  THE   CONTINENTS. 


two  mountain   systems,  was  the  work  of  those  general  forces  which  uplifted  the 
continents. 

4.  Valleys  descending  the  slopes  of  mountains  are  formed  in 
the  same  manner.     In  the  language  of  Dana  :  — 

"  The  gathering  drops  make  the  rill,  and  the  rill  its  little  furrow  ;  rills  combine 
into  rivulets,  and  rivulets  make  a  gully  down  the  hill-side  ;  rivulets  unite  to  form 
torrents,  and  these  work  with  accumulating  force,  and  excavate  deep  gorges  in  the 
declivities.  Other  torrents  form  in  the  same  manner  about  the  mountain  ridge, 
and  pursue  the  same  work  of  erosion  until  the  slopes  are  a  series  of  valleys  and 

ridges,  and   the  summit  a  bold  crest  overlooking  the  eroding  waters 

The   larger  part  of   the   valleys  of   the  world  are   formed  entirely  by  running 
water." 


IV.  <  (mimon  Features  of  Continental  Relief. 

1.  Structure  of  Continents.  Although  there  is  in  each  con- 
tinent a  peculiar  combination  of  mountain  systems,  plateaus,  and 
plains,  giving  it  a  distinctive  character,  yet  there  are  certain  grand 
features  common  to  all. 

Each  continent  has  upon  one  side  of  the  centre  a  great  mass  of 
elevated  lands,  usually  extending  throughout  its  entire  length,  and 
constituting  the  primary  feature  of  its  structure. 

On  the  opposite  side  is  found  a  similar,  though  smaller  and  less 
elevated  mass,  extending  through  but  a  part  of  the  continent, 
and  constituting  the  secondary  feature  of  the  continental  structure. 

Between  the  primary  and  secondary  elevations  is  a  central  depres- 
sion, which  forms  the  third  feature  common  to  all  the  continents. 

2.  Continental  Axes.  The  great  dividing  ridges,  from 
which  the  continent,  as  a  whole,  slopes  in  opposite  directions,  may 
be  called  the  main  axis  of  the  continent.  The  less  highlands,  sepa- 
rating into  opposite  slopes  the  part  of  the  continent  in  which  they 
are  situated,  form  a  secondary  axis. 

The  converging  directions  of  their  fundamental  axes  give  to  the 
continents  their  common  tendency  towards  a  triangular  form  ;  while 
the  peculiar  combination  of  mountain  chains,  plateaus,  and  plains 
in  each  continent,  determines  its  individual  figure  and  contours. 


ANALYSIS  OF  SECTION   IV. 

I.  Plateaus. 

1.  Situation  of  Plateaus. 

a.  Situation  described. 

b.  Examples. 

2.  Surface  of  Plateaus, 

a.  General  character. 

b.  How  plateaus  differ  from  plains. 
3-  Elevation  of  Plateaus. 

a.  Plateaus  of  first  order. 

b.  Plateaus  of  second  order. 

c.  Plateaus  of  third  order. 

4.  Importance  of  Plateaus  in  Structure  of  Continent*. 
5-  Character  of  Plateaus. 

a.  General  character  stated. 

b.  Examples  in  great  plateaus. 

Their  surface.    Their  soil 

II.  Mountains. 

1.  Appearance  of  Mountains. 

2.  Mountain  Chain  Described. 

a.  General  form  and  character. 

b.  Crest. 

c.  Passes. 
3   Mountain  System. 

a.  Consists  of  what. 

b.  Breadth  and  slope. 

c.  Adjacent  regions. 

4.  Formation  of  Mountains. 

a.  Upheaval  how  produced. 

b.  Main  types  of  mountain  chains. 

Names  and  difference  in  height.     Examples. 

5.  Mountains  by  Folding. 

a.  General  character,*, 


b.  Crests. 

c.  Gaps.     Example  In  Appalachian  Mountains. 
6.  Mountains  by  Fracture. 

a-  Ranges. 

b.  Crests. 

III.  Valleys. 

1.  Valleys  Occur  where. 

2.  Valleys  among  Mountain  Ranges. 

a.  Origin  due  to  what. 

b    Subsequent  modifications. 

c.  How  distinguished. 

d.  Valleys  in  mountains  by  folding. 

e.  Valleys  in  mountains  by  fracture. 
3    Valleys  in  Plains. 

a.  Cause. 

b.  Mode  of  formation  described. 

c.  Examples  in  Mississippi  basin. 

Grand  Canon  of  the  Colorado. 
Similar  formations  where 
e    Erroneous  use  of  term  valley.     Example. 
4.  Valleys  Descending  Mountain  Slopes. 

a.  Dana's  description  of  formation. 

b.  Dana's  statement  of  origin  of  valleys. 

IV.  Common  Features  of  Continents. 

1.  Structure  op  Continents. 

a.  Existence  of  features  common  to  all. 

b.  Primary  highlands. 

c.  Secondary  highlands. 

d.  Central  depression. 
8.  Continental  Axes. 

a   Main  Axis. 

b.  Secondary  All*. 

c.  Effect  of  convergence. 

d.  Effect  of  combination  of  relief  forms 


MAP   STUDIES   ON   RELIEF   FORMS. 

Xutk.  —  The  plains  are  represented  on  the  map,  pages  28  and  29,  by  preen  ;  plateaus  of  tbe  second  and 
third  orders  by  brown,  and  those  of  the  first  order  by  white.  The  light  shading,  in  the  representations 
of  mountains,  indicates  the  lower  ranges,  and  heavy  shading  the  higher. 

The  profile  at  the  bottom  of  tbe  map  shows  the  comparative  elevation  of  the  principal  plateaus  and  moun- 
tains of  the  globe.  Their  altitude  can  be  ascertained  by  means  of  the  scale,  which  is  separated  into  parts 
of5,00D  feet  each. 

In  what  part  of  North  America  are  the  great  plains? 

In  wliat  part  of  the  continent  is  the  greatest  highland  region? 

What  mountain  system  included  in  this  region? 

What  mountain  system  near  the  Atlantic  coast? 

How  do  the  Rocky  and  Appalachian  Mountains  compare  in  direction? 

How  do  they  compare  in  height  and  extent? 

What  great  mountain  system  on  the  western  coast  of  South  America? 
What  form  of  relief  prevails  in  the  eastern  part  of  the  continent  ? 
How  do  the  mountains  on  the  plateau  of  Brazil  compare  with  the  Andes  in  direction? 
How  do  they  .compare  with  the  Andes  in  elevation  and  extent  ? 
In  what  part  of  South  America  are  the  great  plains? 

How  (see  profile)  do  the  Kocky  Mountains  compare  with  the  Andes  in  height? 
How  do  the  western  plateaus  of  North  America  compare  in  elevation  with  those  in  the  Andes  ? 

In  what  part  of  Asia  are  the  most  extensive  plains? 
In  what  part  of  the  continent  is  the  plateau  of  Thibet? 
What  two  mountain  systems  border  this  plateau? 

What  mountain  chains  immediately  south  of  the  great  northern  plains  of  Asia? 
What  mountain  chain  and  plateau  between  the  Altai  and  the  Kuenlun  Mountains? 
How  (see  profile)  does  the  plateau  of  Mongolia  compare  in  elevation  with  Thibet? 
What  form  of  relief  predominates  in  the  western  part  of  Asia? 
What  forms  of  relief  predominate  in  the  great  peninsulas  of  Asia? 

In  what  part  of  Europe  are  the  great  plains? 
What  mountains  separate  the  European  plains  from  the  Asiatic? 
In  what  direction  do  the  Ural  Mountains  extend? 
What  form  of  relief  predominates  in  the  southwestern  part  of  Europe? 
What  relief  form  predominates  in  the  peninsula  of  Norway  and  Sweden? 
How  (see  profile)  do  the  plateaus  and  mountains  of  Europe  compare  in  height  with  those  of 
Asia  ? 

What  is  the  dominant  relief  form  in  Africa? 
In  what  part  of  the  continent  are  the  longest  and  highest  mountain  ranges? 
Where  are  the  largest  plains  of  Africa  ? 
What  relief  form  occupies  the  Island  of  Madagascar? 

What  form  of  relief  is  most  extensive  in  Australia? 
Ill  what  part  of  the  continent  are  the  great  plains  ? 
In  what  part  of  the  continent  is  the  principal  elevated  region? 

How  do  the  mountain  ranges  in  the  Islands  of  New  Zealand  compare  with  those  on  the  east- 
ern coast  of  Australia  ? 

How  do  the  mountain  ranges  in  the  Asiatic  islands  compare  in  direction  with  the  chains  on 
the  adjacent  coasts? 


STRUCTURE    OF  THE   NEW   WORLD. 


31 


lo.ooc 
Englft- 


V.  — STRUCTURE  OF  THE  NEW  WORLD. 

Introduction.  The  New  World  as  a  whole  shows  a  marked 
unity  of  structure,  one  common  flan  pervading  the  two  Americas. 
In  each  the  main  axis,  which  extends  unbroken  through  the  entire 
length  of  the  continent,  lies  near  the  western  shore ;  the  secondary 
axis  near  the  eastern.  Vast  low  plains  occupy  the  interior,  but 
the  plains  on  the  seaward  slopes  of  the  axes  are  only  of  limited  extent. 

North  and  South  America, 
however,  differ  greatly  in  the 
details  of  their  structure,  as 
well  as  in  their  climatic  situa- 
tion, each  possessing  peculiar 
characteristics  which  show  it 
to  have  been  constructed  for 
the  performance  of  a  distinct 
part,  both  in  the  realm  of  nature  and  in  the  history  of  human  progress. 


I.  North  America. 

Notk.     Figure  8  represents  to  the  eye  a  section  of  North  America  along  a  line 
connecting  Delaware  and  San  Francisco  Bays.     The  horizontal  base  of  the  drawing 
represents  the  level  of  the  sea.    The  irregular  lop  line  indicates  the  successive  ele- 
vations and  depressions  of  the  surface, 
along  the  line  specified,  the  altitude  of 
which  can  be  ascertained  by  means  of 
the  scale  at  the  margin. 

The  map  exhibits  the  relative  posi- 
tion of  the  great  features  of  continental 
relief,  and  the  altitudes  of  mass  eleva- 
tions. The  mountains  are  represented 
by  straight  or  broken  lines,  the  heavier 
lines  indicating  the  higher  ranges.  The 
dotted  lines  represent  swells  of  land  but 
slightly  above  the  general  level. 

1.  The  Pacific  Highlands, 
which  form  the  primary  feature 
of  North  America,  occupy  al- 
most all  the  western  half  of  the 
continent,  extending  from  the 
Arctic  Ocean  to  the  Isthmus  of 
Panama. 

This  region  consists  of  a  vast 
plateau,  surmounted  by  two  lofty 
mountain  systems  —  the  Rocky 
Mountains  and  the  system  of 
the  Sierra  Nevada — with  nu- 
merous shorter  parallel  ranges 
lying  between  them. 

The  breadth  of  the  plateau, 
between  the  Sierra  Nevada  and 
Rocky  Mountains,  is  not*  lest 
than  600  miles,  and  the  more 
northern  and  southern  portions  have  an  average  breadth  of  about 
300  miles.  The  elevation  increases,  through  a  succession  of  swells 
and  depressions,  from  800  feet  near  the  Arctic  shores  to  8,000  in 
the  table-land  of  Mexico,  whence  it  decreases  rapidly  southward. 

Two  remarkable  depressions  occur  in  the  plateaus  east  and  south- 
east of  the  Sierra  Nevada.  Death  Valley,  into  which  the  Amargoza 
Rivet  flows,  is  situated  east  of  the  highest  part  of  the  Sierra  Nevada. 
It  J  is  about  forty  miles  long  ;  and  its  centre  is,  in  winter,  a  salt  marsh 
whose  surface  is  more  than  100  feet  below  the  sea  level. 


Appalachian 

Mts. 


Great  Central  Plains. 


Atlantic 
Ocean . 


FIG.    8.      NORTH    AMERICA    FROM    WEST   TO   EAST. 


The  Colorado  Desert  is  the  dry  bed  of  an  old  salt  lake,  situated 
west  of  the  lower  Colorado,  and  near  the  head  of  the  Gulf  of  California. 
The  lowest  part  of  its  surface  is  about  300  feet  below  the  sea  level. 

The  Rocky  Mountain  system,  which  forms  the  main  axis  of  the 
continent,  is  composed  of  several  distinct  chains,  approximately 
parallel,  and  bound  together  by  numerous  cross  ranges. 

Although  these  mountains,  in  the  highest  part  of  the  system,  be- 
tween 35°  and  40°  north  lati- 
tude, rise  no  more  than  6,000  or 
8,000  feet  above  the  surround- 
ing  country,    they   are    from 
12,000   to  15,000   feet  above 
the  sea  level.  The  crests  in  this 
part  of  the  system,  are  gener- 
ally high  ;    but  farther  north 
they  are  often  deeply  indented,  and  the  peaks  bold  and  quite  irregular. 
The  Sierra  Nevada   and  Cascade  Mountains   form  the  western 
border  of   the  great  plateau.      Their  eastern  slope  is  short  and  ab- 
rupt, their  base  resting  upon  the  plateau,  which  is  from  2,000  to  4,000 
feet  in  elevation.     The  western  slope  is  long  and  gentle,  descending 
into  extensive  valleys  which  are  but  little  above  the  level  of  the  sea. 
The  Sierra  Nevada  chain  is  lofty  and  continuous,  but  the  Cascade 

is  lower,    and  is    studded  with 


Atlantic  Highlands. 


NORTH  AMERICA. 

The  figures    incUcaie   areraqe  Altitudes 
af  Sut£xjc&    m  English.   Teet . 


numerous  volcanic  cones,  some 
of  which  are  still  active.  The 
highest  peaks  are  from  10,000 
to  15,000  feet  in  elevation. 

Low  mountains,  called  the 
Coast  Ranges,  lie  between  these 
border  chains  and  the  Pacific 
Ocean.  Both,  the  border  and 
the  coast  chains,  appear  to  con- 
tinue northward  to  the  western 
projection  of  the  continent ;  but 
the  Coast  Ranges,  north  of  Cape 
Flattery,  are  broken  into  a  se- 
ries of  islands. 

2.  The  Atlantic  Highlands, 
which  form  the  secondary  fea- 
ture of  the  continent,  extend 
from  the  northern  coast  of  Lab- 
rador nearly  to  the  Gulf  of 
Mexico  ;  approaching,  but  not 
meeting,  the  western  highlands 
on  the  south. 

This  region  consists  of  the 
plateau  of  Labrador,  with  the 
Laurentide  Mountains,  on  the 
north  of  the  St.  Lawrence  ;  and 
the  Appalachian  Mountain  sys- 
tem and  adjacent  low  plateaus,  on  the  south. 

The  Labrador  plateau  is  only  about  2,000  feet  in  elevation  ;  and 
its  mountains,  which  are  generally  parallel  with  the  St.  Lawrence, 
are  rarely  above  4,000  feet. 

The  Appalachian  region  is  composed  of  a  succession  of  low,  par- 
allel mountain  ranges,  separated  by  long,  trough-like  valleys  ;  and  a 
plateau  about  2,000  feet  high,  which  descends  gently  from  the  crest 
of  the  westernmost  range,  towards  the  interior  of  the  continent. 
The  average  height  of  the  mountain  chains  is  but  3,000  feet.    They 


32 


STRUCTURE   OF  THE   NEW   WORLD. 


Andes. 


Plains  of 
El  Gran  Chaco. 


Pacific  Highlands. 
FIG.  9. 


are  lowest  near  the  centre  of  the  system,  in  northern  New  Jersey, 
and  thence  rise  gradually  to  the  north  and  the  south,  attaining  their 
greatest  altitude  near  their  southern  terminus. 

The  system  is  broken  transversely  through  its  entire  breadth  by  a  deep  cleft, 
from  the  centre  of  which  the  Hudson  flows  southward  to  the  SBa,  and  the  waters 
of  Lake  Champlain  northward  to  the  St.  Lawrence. 

East   of  the   Appalachian    Mountains   a  rolling  plain  descends 
gradually,  terminating    in    a    flat 
tide-water  region  adjacent  to  the 
ocean. 

4.  The  Central  Region  of  the 
continent  is  a  great  plain,  which, 
with  but  slight  variations  of  level, 
stretches  from  the  Arctic  shores  to 
the  Gulf  of  Mexico.  A  slight  swell 
near  the  centre,  designated  the 
Height  of  Land,  separates  it  into  two  parts,  one  descending  north- 
ward to  the  Arctic  Ocean ;  the  other,  southward  to  the  Gulf.  This 
swell,  which  connects  the  Atlantic  with  the  Pacific  highlands,  is 
only  from  1,000  to  2,000  feet  above  the  sea  level. 

The  central  plain  is  formed  by 
the  long  gentle  slope  descending 
eastward  from  the  base  of  the 
Rocky  Mountains,  and  the  western 
slope  from  the  Atlantic  highlands. 
On  the  south  their  intersection  is 
marked  by  the  position  of  the  Mis- 
sissippi River. 

On  the  north  a  broad  low  swell, 
approximately  parallel  with  the 
Rocky  Mountains,  extends  from 
Lake  Superior  to  the  Arctic  shores, 
separating  the  northern  plain  into 
two  vast  basins. 

The  western  basin,  which  is  narrow  and 
elongated,  is  connected  with  the  eastern 
by  a  break  in  the  dividing  swell,  through 
which  the  Nelson  River  flows  to  Hudson 
Bay.  The  eastern  basin,  which  is  more 
expanded,  is  partly  below  the  level  of  the 
sea  and  covered  by  the  waters  of  Hud- 
son Bay. 

A  series  of  remarkable  depressions,  oc- 
cupied by  the  great  lakes  of  the  Macken- 
zie and  Saskatchewan  river  systems,  — 
Great  Bear,  Great  Slave,  Athabasca,  and 
Winnepeg  —  marks  the  intersection  of  the 
northern  swell  with  the  slope  from  the 
Rocky  Mountains. 

On  the  Height  of  Land,  near  its  junc- 
tion with  the  northern  swell,  are  three 
vast  depressions,  diverging  from  a  com- 
mon centre,  with  a  depth  reaching  con- 
siderably below  the  level  of  the  sea. 
These  are  filled  by  the  waters  of  the  great  lakes  —  Superior,  Michigan,  and  Huron. 

Similar,  though  less  extensive,  basins  in  the  St.  Lawrence  valley  are  occupied 
by  lakes  Erie  and  Ontario. 

II.  South  America. 

1.  Distinguishing  Featuees.  This  continent  has,  like  North 
America,  the  greater  highland  parallel  with  the  western  shore,  and 
the  less,  with  the  eastern  ;  while  a  vast  central  region  of  low  plains 
stretches  between  them. 


Atlantic  Highlands. 

SOUTH  AMEKICA   FROM    WEST  TO  EAST. 


But  the  western  highland  of  South  America,  the  Andes  Moun- 
tains, is  a  single  narrow  system,  composed  of  two  main  chains  and 
an  intervening  valley,  all  of  great  height ;  while  that  of  North 
America  is  a  vast  plateau,  surmounted  by  two  great  systems  of 
mountains,  hundreds  of  miles  apart  and  of  medium  height. 

The  eastern  highland  is  a  low  plateau,  occupying,  at  its  greatest 
extension,  two  thirds  of  the  breadth  of  the  continent,  while  that  of 

North  America  is  a  narrow  moun- 
tain region. 

Again  the  central  plain  of  North 
Serrade  America  is  divided,  by  distinctly 

Mantiqueira.  . 

Plateau  of  Brazil.  Atianticmai''ied  water-sheds,  into  separate 

0coaQ-  basins  and  slopes ;  and  is  character- 
ized by  numerous  great  depressions, 
in  which  are  formed  the  most  re- 
markable belt  of  lakes  on  the  globe ; 

but  the  great  plains  of   South  America   are  exceedingly  flat,  have 

scarcely  distinguishable  water-sheds,  and  are  destitute  of  great  lakes. 
2.  Primary   Highland.       The  Andes  Mountain  system,  in  the 

larger  part  of  its  extent,  consists  of  two  parallel  chains  whose  crests 

are  separated  by  broad,  plateau- 
like valleys,  from  20  to  60  miles 
wide,  and  from  8,000  to  13,000 
feet  high.  Near  the  northern  ter- 
minus there  are  three  diverging 
chains  instead  of  two,  and  near  the 
southern  there  is  but  one. 

Numerous  cross  swells,  or  moun- 
tain knots,  connect  the  ranges, 
separating  the  high  intervening 
valley  into  a  number  of  distinct 
basins.  The  broadest  and  highest 
of  these  is  the  Plateau  of  Bolivia, 
opposite  the  Gulf  of  Arica,  the 
great  indentation  of  the  Pacific 
coast. 

The  altitude  of  the  Andes  in- 
creases from  the  Isthmus  of  Pan- 
ama southward  to  the  Plateau  of 
Bolivia,  where  the  crests  rise  to 
16,000  feet,  and  the  highest  peaks 
are  from  20,000  to  25,000  feet  in 
elevation.  The  breadth  of  the  sys- 
tem is  only  from  200  to  300  miles. 
The  slopes  are  abrupt  and  deep- 
ly cut  by  transverse  valleys.  No 
longitudinal  valleys  occur  on  the 
western  slope,  and  but  few  on  the 
eastern  slope  of  the  central  Andes. 
The  summit  of  the  ranges  is 
not  a  narrow,  sharp  ridge,  but  is 

often  a  plateau-like  expansion,  sometimes  several  miles  broad,  from 

which  numerous  volcanic  peaks  rise  abruptly. 

2.  The  Secondary  Highland,  called  the  Plateau  of  Brazil, 
has  an  average  elevation  of  only  2500  feet,  and  is  comparative!} 
level.  It  is,  however,  surmounted  at  intervals  by  ranges  of  1«\> 
mountains,  which  are  approximately  parallel,  but  are  connected  a 
the  south  by  cross  ranges  and  swells  of  land,  forming  a  transvevse 
water-shed,  called  the  Serra  dos  Vertentes. 


SOUTH  AMERICA 


The     fi$u.T-c£     tnd-Cccute  average  Altitude* 
of   Su.  r£a£e     in.    E^y lt,%hs    fee t" ■ 


The  highest  and  most  continuous  ranges,  forming  the  secondary 
axis  of  the  continent,  extend  along  the  eastern  coast,  reaching  their 
greatest  elevation  west  of  Rio  Janeiro.  Their  average  altitude  is 
from  4,000  to  6,000  feet,  the  highest  peaks  reaching  nearly  10,000  ft. 

A  subordinate  highland  region,  called  the  Mountain-land  of  Guiana,  lies  in  the 
northern  part  of  the  continent.  It  is  a  low  plateau  covered  with  short  ranges  of 
medium  height,  extending  in  an  east  and  west  direction,  and  increasing  in  eleva- 
tion towards  the  southwest,  where  Maravaca  peak  reaches    8,000  feet. 

3.  The  Central  region  is  chiefly  a  vast  alluvial  plain,  but  few 
hundred  feet  above  the  level  of  the  sea,  and  almost  devoid  even  of 
such  slight  swells  as  divide  the  great  interior  plain  of  North 
America. 

On  the  east  the  plains  of  the  Amazon  are  separated  from  those  of 
the  Orinoco  and  La  Plata  by  the  secondary  highland  regions ;  but 
farther  west  the  three  plains  are  blended  into  one,  with  only  very 
slight  water-sheds  between  them. 


ANALYSIS    OF   SECTION  V. 


Introduction. 

».  Common  plan  of  structure. 

b.  Differences  in  North  and  South  America. 

I.  North  Ameriea. 

1.  Primary  Highlands. 

a.  Position  and  extent. 

b.  Structure. 

c.  Breadth  of  plateau.     Elevation. 

d.  Depressions. 

e    Rocky  Mountain  system. 

Consists  of  what. 

Elevation  of  highest  part- 

Crests  and  peaks. 
f.  Sierra  Nevada  and  Cascade  Mountains. 

East  slope  and  base.     West  ditto. 

Continuity  of  chains. 

Coast  mountains. 

Northward  prolongation. 

2.  Secondary  Highlands. 

a.  Position  and  extent. 

b.  Structure. 

c.  Labrador  plateau  aud  mountains. 

d.  Appalachian  region. 

Structure. 
Elevation. 
Breaks. 

e.  Eastern  slope. 
Central  Region. 

a.  Character.    Dividing  swell. 

b.  Formation  by  slopes. 

Intersection  on  tbe  south. 
Separation  on  tbe  north. 

c.  Depressions. 

In  west  basin. 

In  height  of  land. 

In  St.  Lawrence  valley. 

II.  South  America. 

1.  Distinguishing  Features. 

a.  Position  of  highlands. 

b.  Highlands  compared  with  North  America. 

c.  Central  Plain  ditto. 

2.  Primary  Highland. 

a.  Structure  in  the  larger  part. 

b.  Structure  of  extremities. 

c.  Divisions  of  valley. 

d.  Altitude. 

e.  Breadth. 

f.  Slopes. 

g.  Summit. 

3.  Secondary  Highland. 

a.  Elevation  and  surface. 

b.  Mountains  surmounting  it. 

Character  and  direction. 
Highest  ranges, 
c  Subordinate  mountain  region. 

4.  Central  Region. 

a.  Character. 

b.  Elevation. 

c.  Surface. 


VI.  —  STRUCTURE   OF  ASIA. 

I.  Introduction. 

1.  The  Double  Continent,  Asia-Europe.  Asia  and  Europe 
have,  like  the%wo  Americas,  a  remarkable  similarity  in  their  general 
plan  of  structure,  and  are  so  closely  connected  as  to  form  but  one  great 
continental  mass,  analogous  to  the  New  World.  Yet  each  possesses 
striking  physical  peculiarities  which  secure  to  it  a  marked  individu- 
ality, and  constitute  it  a  distinct  continent. 

Asia  is  the  main  body  of  the  double  continent,  Europe  the  pe- 
ninsular portion.  A  natural  separation  between  them  is  formed 
by  the  belt  of  low,  marine  plains,  east  of  the  Ural  Mountains  and 
river,  and  the  vast  depressions  occupied  by  the  Caspian  and  Black 
Seas. 

2.  Common  Features.  In  both  Asia  and  Europe  the  primary 
and  secondary  highland  regions  extend  east  and  west ;  each  includes 
several  separate  mountain  systems  or  plateaus ;  and  the  secondary 
highlands  are  near  the  centre  of  the  continent. 

The  central  depression  in  each  consists  largely  of  plateaus,  and  is 
small  compared  with  the  extent  of  the  continent,  the  great  plains 
lying  between  the  secondary  highlands  and  the  sea. 

A  series  of  subordinate  elevations  lies  between  the  primary  high- 
lands and  the  sea,  forming  the  great  peninsulas  which  mark  the 
southern  shores  of  both  continents. 

3.  Asia  is  characterized  by  the  division  of  its  mass  into  two 
parts  —  Eastern  and  Western  Asia —  each  of  which  has  a  certain 
individuality  of  character.  The  former  includes  the  great  body  of 
the  continent ;  but  all  the  peculiarities  of  its  structure  are  repeated, 
on  a  smaller  scale,  and  in  a  somewhat  modified  form,  in  the  latter. 

Each  has  its  primary  and  secondary  highlands  crowded  towards 
the  centre,  the  intervening  region  being  a  plateau  ;  large  low  plains 
form  the  northern  slope,  and  smaller  plains  and  peninsular  high- 
lands, the  southern. 

II.  Eastern  Asia. 

1.  The  Interior  of  Eastern  Asia  is  a  vast  square  mass  of  ele- 
vated land,  where  the  primary  and  secondary  highlands,  and  the  in- 
tervening lower  plateaus,  are  all  crowded  within  one  third  of  the 
breadth  of  the  continent.  From  its  margins  the  land  descends  on 
every  side  —  on  the  north  to  the  Arctic  ocean,  on  the  east  to  the 
Pacific,  on  the  south  towards  the  Indian  Ocean,  and  on  the  west  to 
the  low  basin  of  the  Caspian  and  Aral  Seas. 

2.  The  Primary  Highland  region,  which  is  situated  south  of 
the  centre,  is  a  vast  swell  of  land  including  the  highest  mountains 
and  plateaus  of  the  globe.  It  consists  mainly  of  the  Himalaya  and 
Kuenlun  chains,  and  the  intervening  mountainous  plateau  of 
Thibet ;  but  the  lower  plateaus  and  mountains  of  southern  China 
continue  this  feature  of  the  continent  to  the  Pacific  shores. 

Mount  Everest,  in  the  Himalayas,  is  the  highest  mountain  known, 
its  altitude  being  over  29,000  feet.  Many  peaks  in  this  and  the  ad- 
jacent ranges  are  above  25,000  feet.  The  plateau  of  Thibet,  which 
is  surmounted  by  the  Karakorum  Mountains,  scarcely  inferior  to  the 
Himalayas  in  altitude,  is  highest  in  the  western  part,  reaching  in 
some  places  nearly  19,000  feet.     Its  average  height  is  16,000  feet. 

3.  The  Secondary  Highland  is  a  broad  expanse  of  plateaus 
and  mountains,  having  the  Thian  Shan  chain  on  its  southern  mar- 
gin, and  the  triple  chain  of  the  Altais  on  the  northern.  The  high- 
lands are  prolonged,  by  the  Yablonoi  and  lower  ranges,  to  the  north- 
eastern angle  of  the  continent. 


Plains  of  Siberia. 


V>         A    Jt 


The  greatest  altitude  is  attained  in  the  western  part  of  the  Thian 
Shan,  where  the  highest  peaks  are  from  15,000  to  20,000  feet  high. 

The  primary  and  secondary  highlands  converge  on  the  west,  and 
are  connected,  at  the  terminus  of  the  Himalayas,  by  the  high  pla- 
teau of  Pamir.     Both  are  continued  westward,  beyond  the  connect- 
ing plateau,  by  lower   ranges 
which  extend    nearly   to    the 
meridian  of   the  Ural  Moun- 
tains. 

On  the  east  the  Great  Khin- 
gan,  and  other  ranges  having 
a  general  north  and  south  di- 
rection, partially  connect  the 
Yablonoi  with  the  Himalaya 
Moim  tains. 

4.  The  Central  Depression  consists  of  the  great  low  plateau 
of  eastern  Turkestan  and  Mongolia,  between  the  primary  and 
secondary  swells,  which  stretches  without  interruption  from  the  pla- 
teau of  Pamir  on  the  southwest,  to  the  Great  Khingan  Mountains 
on  the  northeast. 

Though  this  vast  basin  is  from  2,000  to  4,000  feet  above  the  sea 
level,  yet  it  lies  from  6,000  to  12,000  feet  below  the  neighboring 
plateau  of  Thibet.  Near 
the  mountains  the  soil  is 
fertile  and  supports  a  large 
population.  In  the  interior 
the  surface  is  generally  cov- 
ered with  sand  and  pebbles, 
forming  the  so-called  des- 
erts of  Gobi  and  Shamo,  yet 
many  portions  producea 
scanty  vegetation. 

The  open  valleys  separat- 
ing the  Thian  Shan  and  Altai 
Mountains,  form  the  main 
connection  between  this  bar- 
ren plateau  and  the  more 
fertile  and  populous  regions 
of  western  and  southern 
Asia. 

5.  The  Slopes.  The 
long  northern  dope  of  east- 
ern Asia  forms  the  vast  Si- 
berian plain.  The  eastern 
half  is  elevated  and  its  sur- 
face is  rugged  or  hilly  ;  but 
the  western  part,  including 
the  steppes  of  the  Obi  ba- 
sin, is  more  level,  and  only 
about  250  feet  in  average 
elevation. 

The  eastern  slope,  extending  from  the  Khingan  and  more  south- 
erly ranges  to  the  Pacific,  is  extremely  varied  in  surface.  It  in- 
cludes the  projections  of  China  and  Manchuria,  formed  by  the  east- 
ward prolongation  of  the  great  continental  swells,  and  an  interven- 
ing region  of  low  alluvial  plains  which  prolong  the  central  depres- 
sion. 

China  is  elevated  and  mountainous  in  the  south  and  west,  many 
of  the  ranges  being  of  great  height ;  but  extensive  low  plains  form 
the  northern  and  eastern  portions.      Manchuria    consists  chiefly 


of  plateaus,  with  alluvial  plains  adjacent  to  the  Amoor  River  and 
its  tributaries,  and  ranges  of  low  mountains  skirting  the  coast. 

The  southern  slope  of  eastern  Asia  comprises  the  low  plains  of 
Hindostan,  at  the  foot  of  the  Himalaya  Mountains  ;  and  two  great 
peninsulas    which    prolong   the   continent   far  into   the  equatorial 

regions. 


Celltr  Depress.  Karakorum.    Himalaya. 


E.  Turkestan 


Thian  Shan 


FIG.   10.      SECTION   OF   ASIA   FROM    NORTH    TO   SOUTH 


C     T     X"    C  O     C     E    A    xr 


^fj*^ 


ASIA 

The  ilgiuts   tnxUxaJjL  outrage  AUitujltJt    ol  £u.r/ixcfc   ui»  K^luh  Tte£ 


The  descent,  through  suc- 
cessive ranges,  from  the  sum- 
mit of  the  Himalayas  to  the 
low  plains  of  the  Ganges  and 
Indus,  which  are  but  little 
above  the  sea  level,  is  short  and 
abrupt.  The  contrast  presented 
by  the  lands  on  opposite  sides 
of  this  great  mountain  system  —  cold,  sterile  plateaus  on  one  side, 
and,  on  the  other,  low  plains  covered  with  luxuriant  tropical  vege- 
tation —  is  not  equaled  elsewhere  on  the  globe. 

The  plains  of  the  Ganges  and  upper  Indus  basins  are  chiefly  un- 
dulating or  alluvial.  East  of  the  lower  Indus  is  an  extensive  bar- 
ren marine  plain,  forming  the  Indian  Desert. 

The  peninsula  of  India  is  formed  by  the  triangular  table-land  of 
Deccan,  south  of  the  Himalayas,  bordered  on  each  side  by  moun- 
tain ranges  —  the  Ghauts 
on  the  east  and  the  west, 
and  the  Vindhya  Moun- 
tains on  the  north.  The 
surface  is  comparatively 
uniform,  though  the  eleva- 
tion gradually  increases 
from  north  to  south. 

The  peninsula  of  Indo- 
China  is  formed  by  a  num- 
ber of  mountain  ranges  di- 
verging from  the  southeast- 
ern angle  of  Thibet,  and 
decreasing  in  elevation  to- 
wards the  south.  The  cen- 
tral range,  much  longer 
than  the  others,  forms  the 
secondary  Malay  peninsula. 
The  western  slope  con- 
sists of  low  mountains  and 
fertile  plains,  gradually  de- 
scending from  the  western 
terminations  of  the  Thian 
Shan  and  Altai  Mountains 
and  the  Plateau  of  Pamir, 
to  the  low,  barren  steppes 
of  Turan,  adjacent  to  the 
Aral  and  Caspian  seas. 


III.  Western  Asia, 

1.  Highlands.  Western  Asia  has  its  primary  and  secondary 
highlands  in  the  lofty  and  mountainous  borders  of  the  Plateau  of 
Iran,  which  extend  from  the  low  plains  of  the  Indus  to  the  western 
extremity  of  the  continent. 

These  two  marginal  swells,  which  are  from  500  to  700  miles  apart 
in  the  east,  converge  towards  the  west,  meeting  in  the  mountain- 
land  of  Armenia,  south  of  the  Caucasus  ;  and,  being  prolonged  be- 


STRUCTURE   OF   EUROPE. 


35 


tween  the  Mediterranean  and  the  Black  Sea,  they  form  the  penin- 
sula of  Asia  Minor. 

The  altitude  of  the  plateau  increases  from  2,500  feet  in  Asia  Mi- 
nor, to  4,000  south  of  the  Caspian  Sea,  and  6,000  or  8,000  at  the 
eastern  terminus.  The  mountains  rise  to  10,000  or  15,000  feet. 
Armenia,  a  volcanic  region,  is  considerably  higher  than  the  adjacent 
portions  of  the  plateau ;  and  Mount  Ararat,  its  highest  peak,  has 
an  elevation  of  16,900  feet. 

As  in  Eastern  Asia,  the  main  axis  lies  on  the  south,  the  secondary 
on  the  north.  Both,  however,  are  pushed  far  to  the  south  of  the 
corresponding  regions  of  Eastern  Asia,  the  secondary  highland  of 
the  one  continuing  the  primary  of  the  other. 

2.  Central  Region.  In  the  eastern  half  of  the  plateau  of  Iran 
is  a  very  marked  central  depression,  lying  from  3,000  to  5,000  feet 
below  the  general  level.  This  region  is  similar  in  character  to  Mon- 
golia, the  surface  consisting  mainly  of  salt  steppes  and  deserts. 

The  altitude,  both  of  the  marginal  swells  and  the  central  depres- 
sion, is  least  in  the  region  directly  south  of  the  Aral  Sea.  There 
the  northern  swell  is  but  2,000,  the  interior  1,500,  and  the  southern 
swell  5,000  feet  in  elevation. 

The  plateau  terminates  on  the  east  with  the  Suliman  and  other 
ranges  of  mountains,  which  rise  abruptly  from  the  low  plains  of  the 
Indus  to  a  height  varying  from  8,000  to  10,000  feet. 

Occasional  passes  in  this  high,  mountainous  border,  form  the  only 
practicable  routes  of  travel  between  the  interior  of  Western  Asia 
and  India.  The  most  important  are  the  Bolan  pass,  near  the  centre, 
and  the  Cabool  or  Peschawer  pass,  near  the  northern  terminus. 

3.  Slopes.  North  of  Iran  is  a  depressed  region  including  the  low 
steppes  south  of  the  Aral  Sea ;  the  small  plains  of  Georgia,  south  of 
the  Caucasus  Mountains ;  the  submerged  basins  of  the  Black  and 
Caspian  seas  ;  and  the  low  plains  of  the  Amoo  Daria. 

South  of  the  plateau  is  a  corresponding  depression,  including  the 
low  plains  of  the  Euphrates  and  Tigris  rivers,  and  the  submerged 
basin  of  the  Persian  Gulf.  The  plains  which  are  undulating  or 
alluvial,  were,  in  ancient  times,  the  seat  of  mighty  nations ;  and, 
being  irrigated  with  cai*e,  they  were  surpassingly  fertile.  Now,  de- 
prived of  moisture  other  than  the  winter  rains  afford,  they  are,  dur- 
ing the  larger  part  of  the  year,  a  parched  and  barren  waste,  except 
on  the  borders  of  the  rivers. 

The  peninsula  of  Arabia  is  an  immense  plateau,  separated  from 
the  table  land  of  Iran  by  the  Persian  Gulf  and  the  low  plains  of 
the  Tigris  and  Euphrates,  and  connected  with  the  mountain  region 
of  Asia  Minor  by  the  plateau  and  mountains  of  Syria. 

The  surface  in  the  interior  is  varied  by  ranges  of  hills  and  moun- 
tains, which,  however,  do  not  rise  much  above  the  general  level. 
The  elevation  gradually  increases  from  north  to  south,  being  great- 
est in  the  southeastern  part.  A  large  portion  of  Arabia,  is  nearly 
rainless,  and  consequently  a  desert ;  but  the  mountainous  regions  on 
the  southern  coast  receive  copious  rains,  and  are  more  productive. 

The  valley  of  the  Dead  Sea  and  the  Jordan,  amidst  the  highlands 
of  Syria,  is  one  of  the  most  remarkable  depressions  known.  (See 
page  51,  Topic  III.,  3.) 


ANALYSIS  OP  SECTION  VI. 

I.  Introduction. 

1.  Individuality  of  Asia  and  Europe. 

a.  Structure  and  connection. 

b.  Division. 

2.  Common  Features. 

a.  Highlands. 


b.  Central  regions.. 

c.  Great  plains. 

d.  Subordinate  elevations. 
Asia  how  Characterized. 

a.  Division  of  mass. 

b.  Resemblance  in  structure. 


11 


Eastern  Asia. 

1.  Interior. 


a.  Character. 

b.  Slopes. 

2.  Peimart  Highland. 

a.  Situation  and  comparative  elevation. 

b.  Consists  of  what. 

c.  Altitude  of  mountains  and  plateau. 

3.  Secondary  Highland. 

a.  Structure. 

b.  Altitude. 

c.  Convergence  and  connection  of  highlands. 

d.  Westward  prolongation. 

e.  Eastern  connecting  ranges. 

4.  Central  Depression. 

a.  Character  and  extent. 

b.  Altitude. 

c.  Surface. 

d.  Connections  westward. 


6.  Slopes. 


a.  Northern  slope,  extent  and  character. 

b.  Eastern  slope,  consists  of  what. 

Manchuria,  China. 

c.  Southern  slope,  consists  of  what. 

Contrasts  presented. 
Plains  of  Ganges  and  Indus. 
Peninsula  of  India. 
Peninsula  of  Indo  China. 

d.  Western  slope. 


III.  Western  Asia. 


1.  Highlands. 

a.  Where  situated. 

b.  Convergence  and  prolongation. 

c.  Altitude. 

d.  Position  of  axes. 

2.  Central  Region. 

a.  Position  and  relative  elevation. 

b.  Altitude,  where  least. 

c.  Eastern  terminus. 

d.  Routes  of  travel  between  plateau  and  plains 


3.  Slopes. 


a.  Northern  slope,  consists  of  what. 

b.  Southern  slope,  consists  of  what. 

c.  Plains.    Peninsula  of  Arabia. 


VII.  — STRUCTURE  OF  EUROPE. 

I.  Characteristic  Structure. 

1.  Eueope  is  characterized  by  its  small  size,  the  extreme 
irregularity  of  its  outline,  and  the  extent  to  which  it  is  penetrated 
by  arms  of  the  sea.  Nearly  one  fourth  of  the  entire  area  of  the 
continent  consists  of  peninsulas,  yet  all  these  peninsulas  together  do 
not  equal  Arabia  in  area. 

Europe  resembles  Asia  in  the  position  and  direction  of  its  axes, 
the  limited  extent  of  the  region  between  them,  and  the  subdivision 
of  each  of  its  principal  features  into  a  number  of  distinct  regions. 

2.  The  Primary  Highland  region  of  Europe  is  even  more 
broken  and  irregular  than  that  of  Asia.  The  Alps  form  the  central 
and  highest  portion.  The  Pyrenees  and  Cantabrian  Mountains,  on 
the  northern  border  of  Spain,  prolong  the  main  axis  to  the  Atlantic 
shores ;  and  the  Balkan,  south  of  the  Danube,  continue  it  to  the 
Black  Sea.  All  these  mountain  systems  have  numerous  practicable 
passes,  and  are  separated  one  from  another  by  low  valleys  or  small 
plains. 

The  Alps,  an  exceedingly  broken  mountain  system,  have  an  aver- 
age elevation  of  10,000  to  12,000  feet,  about  equal  to  that  of  the 
Rocky  Mountains  and  the  Sierra  Nevada.  The  loftiest  peak  is 
Mont  Blanc,  15,780  feet  high.  The  passes  range  from  5,000  to  11,- 
000  feet  in  elevation. 


36 


STRUCTURE   OF  EUROPE. 


SAXONY. 

Harz  Mts.    Thuringiar. 
Northern  Plains.  Forest. 

1  1 


The  Pyrenees  are  also  rugged  and  broken,  but  are  considerably 
less  elevated  than  the  Alps.  The  crest,  in  the  highest  portion,  is 
about  8,000  feet  high;. the  highest  peak,  11,168  feet.  The  Canta- 
brian  Mountains  are  somewhat  lower  than  the  Pyrenees. 

The  Balkan  Mountains,  connected  with  the  Alps  by  the  high- 
lands on  the  south  of  the  middle  Danube,  are  still  lower,  their 
average  elevation  being  only  about  5,000  feet. 

3.  The  Secondary  Highlands  consist  of  the  Carpathian,  the 
Sudetic,  and  Riesen  Mountains,  and  lower  ranges  extending  nearly 
to  the  shores  of  the  North  Sea. 

This  series  of  mountain  ranges  forms  a  dividing  line  between 
Northeastern,  or  Low  Europe,  and 
Southwestern,  or  High  Europe  ;  the 
former  being  a  great  low  plain,  while 
the  latter  is,  in  general,  elevated 
and  mountainous. 

4.  The  central  region,  lying 
between  the  primary  and  the  sec- 
ondary highlands,  consists  of  low  plateaus  and  mountain  ranges,  and 
small  plains. 

Its  structure  is  rendered  extremely  complex  by  the  prevalence  of 
two  widely  differing  directions  in  the  trend  of  the  mountains.  Those 
east  and  northeast  of  the  Alps  continue  the  direction  of  the  Asiatic 
systems,  from  southeast  to  northwest,  converging  and  diminishing 
in  elevation  towards  the  west. 

The  Alps  and  the  more  westerly  chains  extend  from  southwest 
to  northeast,  diverging  eastward.  The  two  series  intersect  north  of 
the  Alps,  forming  a  great 
number  of  small  inclosed 
basins,  which  give  to  Cen- 
tral Europe  its  peculiar 
character.  (This  peculiar- 
ity of  structure  is  shown  by 
the  Structure  Map  of  Cen- 
tral Europe,  page  37.) 


II.  Contrasting  Divisions. 

1.  High  Europe  as  a 
whole,  including  the  pri- 
mary and  secondary  high- 
lands and  the  central  re- 
gion, is  separated  into  three 
main  divisions  by  the  val- 
leys of  the  Rhone,  the  Sa- 
one,  and  the  Middle  Rhine, 
on  the  west,  and  the  plains 
of  Moravia,  at  the  eastern 
extremity  of  the  Alps. 

The  middle  section  is  the 
most  characteristic  of  the  continent.     It  has  for  its  base  the  main 
body  of  the  Alps ;  at  the  north  is  a  low  plateau  gently  sloping  in 
terraces  to  the  maritime  plains  of  the  North  Sea  and  the  Baltic ; 
at  the  south,  the  low  plains  of  the  Po. 

The  surface  is  greatly  diversified  by  the  numerous  ranges  of  moun- 
tains intersecting  each  other  north  of  the  Alps.  The  most  marked 
of  its  subdivisions  are  the  plateaus  of  Switzerland  and  Bavaria,  the 
broad  valley  of  the  Middle  Rhine,  and  the  basin  of  Bohemia. 

The  western  section  has  the  Cevennes  Mountains  and  adjacent 


Plat,  of 
Bavaria. 


FIG.   11.     SECTION  OF  EUROPE  FROM  NORTH  TO  SOUTH. 


plateaus  for  its  central  mass,  with  the  valley  of  the  Rhone  on  the 
east,  and  the  Atlantic  plains  on  the  west  and  north. 

The  eastern  section  has  for  its  centre  the  TransyWanian  Alps 
and  Plateau,  with  the  Carpathian  Mountains  on  the  north,  the  low 
plains  of  Roumania  on  the  east,  and  the  Hungarian  plains  on  the 
west. 

The  barriers  between  these  regions,  sufficient  to  give  each  a  dis- 
tinctive character,  are  not  sufficient  to  isolate  them  one  from  another, 
or  to  render  intercommunication  so  difficult  as  between  the  different 
regions  of  central  Asia. 

Each  of  the  main  divisions  of  High  Europe  is  prolonged  southward 

by  a  great  peninsula.  The  Hellenic 
peninsula,  between  the  Black  and 
Adriatic  Seas,  prolongs  the  eastern 
section  ;  Italy,  the  middle  section ; 
and  the  Spanish  peninsula,  the 
western.  These  peninsulas  present 
a  marked  contrast  to  those  of  Asia 
in  regard  to  size,  but  an  equally  marked  similarity  in  general  struc- 
ture, position,  and  character. 

The  Hellenic  peninsula,  formed  by  mountain  ranges  diverging 
from  the  east  end  of  the  Alps,  corresponds  to  the  Asiatic  peninsula 
>f  Indo-China  ;  but  its  mountains  are  lower,  and  many  transverse 
chains  in  the  eastern  part,  complicate  its  structure,  and  render  its 
outline  much  more  irregular. 

The  Italian  peninsula  corresponds  in  position  to  the  peninsula 
of  the  Deccan,  in  Asia,  but  differs  from  the  latter  in  having  for  its 

centre  an  elongated  moun- 
tain chain  instead  of  a  pla- 
teau. It  consists  of  the 
Apennine  range  and  its 
slopes,  the  range  being 
forked  near  the  southern 
terminus.  The  Apennines 
are  connected  with  the 
Alps  only  at  their  north- 
western extremity. 

Between  this  chain  and 
the  Alps  are  the  low  plains 
of  the  Po,  corresponding  in 
position  and  character  to 
those  of  the  Ganges  in  A  sia, 
yet  presenting  a  much  less 
striking  contrast  to  the  pla- 
teaus north  of  the  Alps 
than  is  exhibited  by  the  cor- 
responding regions  of  Asia. 

The   Spanish  peninsula 

corresponds   to    Arabia   in 

position,    in  general  form, 

in  regularity  of  outline,  and  in  the  elevation  of  its  entire  mass.     It 

is  a  great  plateau,  highest  in  the  northeast,  with  the  southwestern 

portion  broken  by  parallel  ranges  of  mountains. 

2.  Low  Europe.  The  great  European  plain  extends,  with 
scarcely  varying  elevation,  from  the  secondary  axis,  northward  to 
the  Arctic  shores,  and  eastward  to  the  Ural  Mountains. 

This  plain  is  slightly  elevated  in  the  centre,  the  highest  part 
being  the  Valdai  Hills,  only  1,100  feet  above  the  sea  level.  They 
rest  upon  a  slight  swell  of  land  which  separates  the  streams  enter- 


38 


AFRICA    AND   AUSTRALIA. 


ing  the  Baltic  and  White  Seas  from  those  flowing  into  the  Black 
Sea  and  the  Caspian.  This  swell  continues  westward,  through  the 
plains  south  of  the  Baltic,  to  the  peninsula  of  Denmark,  but  forms 
only  a  slight  obstacle  in  the  path  of  streams. 

Low  Europe  is  bordered  on  every  side  by  mountain  regions.  On 
the  east  are  the  Urals,  on  the  south  the  Caucasus,  on  the  southwest 
the  secondary  highlands  of  the  continent,  and  on  the  northwest  the 
Scandinavian  highlands.  Depressions  occupied  by  inland  seas,  — 
namely,  the  Caspian,  the  Black,  the  Baltic,  and  the  White  Sea,  — 
separate  these  elevated  regions  one  from  another,  forming  so  many 
doorways  of  communication  with  the  outer  world. 

The  Scandinavian  Alps  form  a  large  part  of  the  peninsula  west  of 
the  Baltic.  They  rise  abruptly  from  the  Atlantic  shores,  and  are 
deeply  cut  by  transverse  valleys,  with  perpendicular  walls  often 
several  thousand  feet  high.  Partially  submerged,  and  admitting 
the  sea  to  the  heart  of  the  mountain  mass,  these  valleys  give  rise  to 
those  deep,  narrow  bays,  called 
fiords,  which  are  so  characteris- 
tic of  the  Norwegian -coast. 


Atlantic  Ocean. 


Mozamba 
Ridge. 


The  British  Isles  form  properly  a 
part  of  the  continental  plain,  sepa- 
rated from  the  main  land  by  the  sub- 
mergence of  a  portion  of  its  surface. 


i.  Central  Region. 

a.  Consists  of  what     Structure,  how  complicated. 

b.  Direction  of  ranges.     Intersection  of  ranges.    Slopes. 
II.  Contrasting  Divisions. 

1.  High  Europe.    Main  Divisions. 

a.  Middle  section.     Structure.     Surface. 

b.  Western  section.     Structure. 

c.  Eastern  section.     Structure.     Barriers  between  sections. 

d.  Peninsulas. 

Comparison  with  Asiatic  peninsulas. 
Hellenic  peninsula.     Italy.    Plains  of  Po. 
Spanish  peninsula. 

2.  Low  Europe 

a.  Extent.     Highest  part.     Dividing  swell. 

b.  Borders.     Scandinavian  peninsula.     Fiords. 

c.  British  Isles. 

8.    SUMMARY. 

a    Subdivisions  compared  with  those  of  Asia. 
b.  Low  and  High  Europe  compared. 


VIII.  —  AFRICA    AND    AUSTRALIA. 

I.  Africa. 

1.  Africa  is  characterized,  in  its  structure,  by  the  combina- 
tion  of  the  plan  of  the  Old  World  (Asia-Europe)  with  that  of  the 

New. 

In  the  northern  half  of  the 


Western  Swell. 
FIG.  12. 

These  submarine  plains  which  form  the 
base  of  the  islands,  are,  in  the  North  Sea,  only  from  200  to  300  feet  below  the  sur- 
face. They  extend  westward,  from  40 
to  60  miles  beyond  the  British  Isles, 
to  a  well  defined  line,  where  an  ab- 
rupt descent  marks  the  termination 
of  the  European  continent  and  the 
commencement  of  the  deep  basin 
of  the  ocean. 

3.  Summary.  The  subdivis- 
ions of  this  continent,  no  less 
numerous  than  those  of  Asia, 
differ  from  the  latter  in  their 
smaller  area,  in  the  milder 
contrasts  between  adjacent  re- 
gions, and  in  the  facility  of 
communication  between  them. 

Low  and  High  Europe,  how- 
ever, present  a  much  greater 
contrast  in  structure  than  East- 
ern and  Western  Asia.  Low 
Europe  is  one  vast  plain,  sur- 
rounded by  mountain  chains, 
but  nearly  uniform  in  surface 
and  character,  and  without 
marked  natural  subdivisions  ; 
while  High  Europe  is  separated 
into  a  great  number  of  distinct 
physical  regions,  diverse  in 
structure  and  character.  East- 
ern and  Western  Asia,  on  the  contrary,  differ  little  except  in  the 
magnitude  of  features  of  structure  common  to  both. 

analysis  of  section  vii. 

I.  Characteristic  Structure. 

1.  Characteristics  op  Europe. 

a.  Characteristics  enumerated. 

b.  Extent  of  peninsulas.    Resemblance  to  Asia. 

2.  Primary  Highlands. 

a.  General  character.    Mountain  chains  included. 

b.  Passes  and  separation  of  chains. 

c.  Elevation  of  Alps. 

Average.     Highest  peak.     Passes. 

d.  Elevation  of  Pyrenees.    Elevation  of  Balkan  Mountains. 

3.  Secondary  Highlands. 

a.  Consists  of  what.     Division  formed  by  these  chains. 


SECTION  OF   AFRICA   FROM    WEST  TO   EAST. 


Indian  Ocean. 

10.000 
Engl.ft 

continent,  the  highlands  extend 
east  and  west,  causing  the 
great  westward  projection  into 
the  Atlantic. 

In  the  southern  half,  as  in  the  New  World,  the  highlands,  both 
primary  and  secondary,  extend  north  and  south  ;  but  the  former  is 

on  the  eastern  shore  (see  map), 
the  latter  on  the  western,  while 
in  the  two  Americas  the  re- 
verse is  true. 

The  two  halves  of  the  conti- 
nent are  bound  together  by  a 
northward  extension  of  the 
primary  highland  of  the  south- 
ern division,  which,  continuing 
nearly  to  the  Mediterranean, 
becomes  the  main  axis  of  Af- 
rica as  a  whole. 

The  central  regions,  occupy- 
ing the  larger  part  of  the  con- 
tinent, though  considerably 
lower  than  the  border  swells, 
are  yet,  in  general,  much  above 
the  sea  level.  Hence  the  en- 
tire continent  is  really  a  vast 
plateau  without  extensive  low- 
lands.    (See  Fig.  12.) 

II,  South  Africa. 


The   ftgwrea  tndtuiat*  a*wq^»  ALtUMxles 
o£  Sttrfctce.     in    English    Feet?  . 


1.  The  primary  highland 
lies  near  the  eastern  coast,  and 
extends  from  the  southern  ex- 
tremity of  the  continent  nearly  to  the  Mediterranean.  It  consists  of 
abroad  belt  of  land  somewhat  above  the  general  level,  surmounted, 
in  various  portions,  by  irregular  ranges  and  groups  of  mountains. 

The  highest  part,  including  the  plateaus  of  Abyssinia  and  Kaffa, 
and  an  adjacent  mountainous  region,  lies  north  of  the  equator.  The 
plateaus  have  an  average  elevation  of  6,000  to  7,000  feet ;  while  the 
highest  mountains  rise  to  15,000  feet.  Immediately  south  of  the 
equator,  on  the  same  line,  are  the  volcanoes  of  Kenia,  Kilima-Njaro, 
and  Ngai,  the  highest  peaks  in  Africa,  which  reach  an  elevation  of 
nearly  19,000  feet  above  the  sea  level. 


AFRICA  AND   AUSTRALIA. 


39 


In  the  southern  part  of  the  great  eastern  swell,  deep  breaks  occur 
through  which  the  Zambesi  and  Limpopo  Rivers  pass  eastward  to 
the  sea.  Beyond  these  breaks  southward,  a  nearly  continuous  moun- 
tain region,  including  the  Quathlamba,  Sneeuw,  and  Nieuweveld 
.Mountains,  extends  to  the  Cape  of  Good  Kope  on  the  Atlantic  coast. 

Tlie  secondary  highland  is  similar  in  character  to  the  primary, 
but  is  less  elevated  and  less  mountainous.  The  highest  mountains 
are  the  Cameroons,  an  isolated  group  of  volcanic  peaks  north  of  the 
equator,  13,000  feet  high.  The 
primary  and  secondary  high- 
lands meet  on  the  south,  form- 
ing a  continuous  plateau,  5,000 


Indian 
Ocean. 


Western  Highlands 


Eastern  Highlands. 


Central  Depression. 


Engl. ft 


r-^— ^  --  —  --—: -- 


feet  in  elevation,  which  fills  all 

that  part  of  the  continent  lying  south  of  the  Tropic  of  Capricorn. 

The  central  region,  though  a  plateau,  is  from  2,000  to  3,000 
feet  lower  than  the  marginal  swells.  It  extends  from  Lake  Nganfi 
northward,  expanding  and  decreasing  in  elevation  as  the  highlands 
diverge  ;  and  is  separated,  by  a  transverse  swell,  into  two  basins,  the 
northern  of  which  contains  a  great  number  of  lakes. 

III.  North  Africa. 

1.  Highlands.  Northern  Africa  has  its  two  border  highlands, 
in  the  Atlas  Mountains  and  plateau  on  the  north,  and  the  Kong 
Mountains  on  the  south,  both 


FIG.   13.      AUSTRALIA    FROM    WEST   TO   EAST. 


"* — ^3^3. 


of  which  are  continued  east- 
ward, by  minor  elevations,  to 
the  main  continental  axis. 

The  average  elevation  of  the 
Great  Atlas  plateau  is  about 
3,000  feet,  the  mountains  being 
from  5,000  to  7,000  feet.  In 
the  High  Atlas  of  Marocco 
some  peaks  reach  13,000  feet. 

The  Kong  Mountains  aver- 
age 3,000  feet,  while  the  high- 
est peaks  may  reach  10,000. 

The  greatest  altitudes  of  the 
continent,  exclusive  of  volcanic 
peaks,  occur  where  the  eleva- 
tions which  prolong  the  Kong 
highlands,  meet  the  main  con- 
tinental axis,  in  the  plateau  of 
Abyssinia. 

At  the  southern  foot  of  the 
Atlas  Mountains,  and  of  the 
more  easterly  elevations  on  the 
Mediterranean  shores,  on  a  line 

with  the  Gulfs  of  Cabes  and  Sidra,  is  a  remarkable  belt  of  depres- 
sions, some  of  which  are  more  than  300  feet  below  the  sea  level. 
The  temporary  Lake  Melrir,  south  of  the  eastern  part  of  the  Atlas 
region,  is  280  feet,  and  the  great  valley  south  of  the  plateau  of 
Barca,  340  feet  below  the  level  of  the  sea.  On  the  same  line,  to- 
wards the  Nile,  are  several  of  the  best  known  oases  of  northern 
Africa,  —  including  Aujila,  Siwa,  and  the  Natron  Lakes,  — all  of 
which  lie  from  100  to  200  feet  below  the  sea  level. 

On  the  eastern  margin  of  the  Abyssinian  plateau  are  the  low  val- 
leys of  Lake  Assal  and  the  Ha  wash  River,  both  of  which  are  below  the 
sea  level.  The  valley  of  Assal,  or  the  salt  plain,  35  miles  long  by  15 
wide,  is  not  less  than  200  feet  below  the  level  of  the  Mediterranean. 


2.  The  central  region  is  the  broad  plateau  of  the  Sahara, 
stretching,  with  little  variation  of  level,  from  the  Nile  valley  to 
the  Atlantic  shores.  Its  average  elevation  is  1,500  feet,  but  the 
northern  and  southern  margins  are  considerably  lower  than  the  inte- 
rior. 

The  surface  of  the  Sahara  is  varied  by  occasional  higher  plateaus, 
from  4,000  to  5,000  feet  in  altitude,  and  groups  or  short  ranges  of 
mountains  sometimes  reaching  6,000  feet.    It  consists  almost  wholly 

of  sand  and  rocks,  and  forms 
the  most  extensive  and  com- 
plete desert  upon  the  face  'of 
the  earth.  Fertility  is  con- 
fined to  oases,  situated  in  the 
depressions  on  its  borders  and  around  the  mountains  of  the  interior. 

IV.  Australia. 

1.  General  Plan.  Australia  greatly  resembles  Southern  Africa 
in  its  general  plan  of  structure,  but  differs  in  consisting  principally 
of  low  plains,  and  in  the  surface  of  the  northern  portion  being  gen- 
erally the  more  elevated.  Its  great  features  of  structure  are  no  less 
distinctly  marked  than  those  of  the  larger  continents.     (Fig.  13.) 

2.  The  Primary  Highlands,  as  in  Africa,  lie  near  the  eastern 
coast  of  the  continent,  extending  through  its  entire  length ;  and  are 

prolonged  on  the  north,  forming 


AU8THALIA 


2ne  figure*    md.i<cate    average  AlUix^aLea 
Qt    "Sui-/oce      in    English    feet-. 


the  York  peninsula.  The  south- 
ern half  is  a  narrow  mountain 
system  of  considerable  eleva- 
tion ;  while  the  northern  half 
is  a  broad  plateau,  gradu- 
ally increasing  in  elevation  to- 
wards the  west  and  the  north. 

The  highest  portion  is  the 
range  of  Australian  Alps,  the 
average  elevation  of  which  is 
about  5,000  feet,  the  highest 
peaks,  Hotham  and  Kosciusko, 
reaching  over  7,000  feet. 

3.  The  Secondary  High- 
land, which  skirts  the  western 
and  northwestern  shores,  is  a 
region  of  low  plateaus,  with 
occasional  groups  and  short 
ranges  of  mountains  not  more 
than  3,800  feet  above  the  sea 
level.  The  peninsular  projec- 
tion of  Arnhem  land,  at  its 
northern  terminus,  is  a  plateau 
from  3,000  to  4,000  feet  in  altitude. 

4.  The  central  depression  is,  as  far  as  known,  a  great  plain, 
varying  but  little  in  general  elevation.  In  the  north  a  slight  swell 
connects  the  primary  and  secondary  highlands,  giving  the  interior 
a  gentle  descent  southward. 

The  western  part  of  the  continent  has  not  been  sufficiently  explored  to  enable 
one  to  give  the  details  of  its  structure  and  character.  The  interior  is  believed 
to  be  without  high  mountains,  comparatively  uniform  in  surface,  and  for  the  most 
part  sandy  or  stony,  and  nearly  desert. 

The  basin  of  the  Darling  and  Murray  rivers  is  the  best  known 
portion  of  Australia,  and  is  a  region  of  considerable  fertility.  The 
country  immediately  west  of  the  Murray  and  lower  Darling  is  quite 
rugged,  its  surface  being  diversified  by  several  short  ranges  of  low 


40 


LAWS    OF   RELIEF. 


mountains.  Extensive  depressions  occur  in  the  same  region,  and  are 
occupied  by  Spencer  Gulf,  and  Lakes  Eyre,  Torrens,  and  Gairdner, 
the  largest  known  lakes  in  Australia. 


ANALYSIS  OF  SECTION   VIII. 

I.  Characteristics  of  Africa. 

1.  Plan  of  Structure. 

a.  North  Africa.    South  Africa. 

b.  Two  divisions  how  connected. 

2.  Position  of  Axes. 

8-  Character  of  Central  Regions. 

II.  South  Africa. 

1.  Primary  Highland. 

a.  Position,  extent,  and  character. 

b.  Highest  portion.    Southern  part. 

2.  Secondary  Highland. 

a.  General  character. 

b.  Highest  mountains. 

c.  Junction  with  main  axis. 

3.  Central  Region. 

a.  Character  and  elevation. 

b.  Position  and  slope.     Division 

III.  Northern  Africa. 

1.  Highlands. 

a.  Position  and  extent. 

b.  Atlas  region,  elevation. 

c.  Kong  region,  elevation. 

d.  Greatest  altitudes  of  the  continent. 

e.  Depressions  near  northern  highland. 

"  "      Abyssinia 

2.  Central  Region. 

a.  Extent  and  elevation. 

b.  Nature  of  surface.    Fertility. 

IV.  Australia. 

1.  General  Plan. 

a.  Resemblance  to  Africa. 

b.  Differences. 

c.  Distinctness  of  features  of  structure. 

2.  Primary  Highland. 

a.  Position  and  extent. 

b.  Character. 

c.  Elevation. 

3.  Secondary  Highland. 


4.  Central  Region. 


Position  and  character. 

General  character  and  slope. 
Western  half  of  continent. 
Basin  of  Murray  and  Darling. 
Region  directly  west  of  basin. 


IX.    LAWS   OF  RELIEF. 


Great  Basin. 


Ocean. 


r-*-:-m 


FIG.  14. 


Main  Axis. 
TYPICAL   FORM   OF   CONTIN 


I.  Typical  Structure  of  Continents. 

A  primary  highland  region  upon  one  side,  a  secondary  one  on  the 
opposite  side,  trending  towards  the  primary,  and  a  depression  be- 
tween  the    tWO,    is    the    typical         Sierra  Nevada.  Rocky  Mts. 

structure  of  a  continent.     An 
island,  however  great  its  ex-  Pa 
tent,  does  not  show  this  con- 
formation. 

The  two  Americas  and  Aus- 
tralia exhibit  this  plan  of  structure  in  its  simplest  form  ;  but,  as  we 
have  seen,  it  is  distinctly  traceable  through  the  more  complicated 
reliefs  of  Asia  and  Europe,  and  the  massive  forms  of  Africa. 

II.  Position  of  Main  Axis. 

The  Main  Axis  in  every  continent  is  placed  outside  of  the  centre, 
and  near  one  of  the  shores  ;  thus  the  continent  is  divided  into  two 
slopes,  unequal  in  length  and  inclination. 

In  North  America,  for  example,  the  Rocky  Mountains,  which  sep- 
arate the  Pacific  and  Atlantic  slopes,  are  over  2,000  miles  from  the 


Atlantic  shore  and  but  800  from  the  Pacific.  Thus  the  western 
slope  has  but  two  fifths  of  the  length  of  the  eastern. 

In  South  America  the  inequality  is  still  greater.  The  crest  of 
the  Andes,  in  which  the  Amazon  River  rises,  is  scarcely  more  than 
100  miles  from  the  Pacific,  while  it  is  more  than  2,500  from  the: 
Atlantic. 

The  shorter  slopes  of  Asia-Europe  consist  almost  exclusively  of 
peninsulas;  and  those  of  Africa  and  Australia  are  scarcely  more 
than  the  eastern  slope  of  the  main  axis  itself. 

III.  Direction  of  Elevations. 

All  the  great  mountain  systems  of  the  globe  extend  in  one  of  two  \ 
general  directions,   approximately  at   right   angles   to   each  other. 
The  same  is  necessarily  true  of  the  general  coast  lines  of  the  conti- 
nents. 

They  extend  either  east  and  west,  with  a  slight  deviation  to  thej 
north  or  south,  hence1  in  a  direction  nearly  parallel  to  the  ecliptic ;] 
or  north  and  south,  slightly  deviating  to  the  east  or  west,  and  there- 
fore on  a  line  at  right  angles  to  the  former.     The  Himalayas,  the 
Alps,  and  the  Atlas  Mountains  are  examples  of  the  east- west  direc-; 
tion  ;  the  Rocky  Mountains,  the  Andes,  and  the  Blue  Mountains  of 
Australia  have  the  north-south  direction. 

Distinguished  geographers  in  the  last  century  had  already  noticed 
these  two  prevailing  directions,  and  designated  them  the  parallel] 
and  the  meridian  direction.  A  more  correct  designation,  however, 
would  be  Ecliptic  and  Arctic  circle  directions.  For  the  one  makes 
an  angle  with  the  equator  approximately  equal  to  that  of  the  j 
ecliptic,  while  the  other,  at  right  angles  to  the  ecliptic,  is  indicated 
by  great  circles  tangent  to  the  Arctic  circle. 

IV.  Contrasting  Plans  in  Old  and  New  Worlds. 

In  the  New  World  the  north-south,  or  arctic  circle  direction} 
prevails  alone  ;  all  the  great  lines  of  elevation  extending  in  that  di-\ 
rection.     In  the  Old  World,  the  east-west,  or  ecliptic,  direction 
predominates,  but  is  repeatedly  intersected  by  the  other. 

This  law  explains  the  remarkable  simplicity  of  structure  in  the 
New  World,  and  the  complexity  in  the  Old. 

In  the  New  World  all  the  great  mountain  systems  have  but  one! 
direction,  producing  that  elongation  southward  so  characteristic  of  I 
the  American  continents. 

The   east-west  direction  is  found  in  the  mountains  of  Northern  J 
Appalachian  Venezuela   and  Guiana  ;    and  j 

Mts"      ocean'0  m  sngn*  swells,  forming  second- 1 
u  ary  water-sheds,  like  the  Height  I 

'fofo*  m —  of  Land  in  North  America,  and! 
the  central  water-shed  of  the  I 
Table-land  of  Brazil  in  South 
America.  Even  these  do  not  intersect  the  main  axes  of  the  cob 
tinent,  and  are  scarcely  sufficient  to  produce  an  entire  separation  be- 
tween the  regions  on  opposite  sides  of  them. 

Hence  few  and  vast  physical  regions,  determined  by  the  main 
continental  axes,  and  a  remarkable  unity  in  the  general  structure, 
is  the  rule  of  the  New  World. 

2.  In  Asia-Europe,  the  dominant  mass  of  the  Old  World,  the 
main  body  is  due  to  plateaus  and  mountain  chains  of  the  east- 
west  direction ;  but  many  long  and  lofty  chains  of  the  north-south 
direction  cross  the  continents,  dividing  them  into  numerous  physical 
regions  diverse  in  character ;  and,  projecting  into  the  sea,  these  trans- 


Basin  of  Mississippi. 


Central  Depression.  Secondary  Axis. 

ENTS   SHOWN  IN  NORTH  AMERICA. 


i 


. 


LAWS   OF   RELIEF. 


41 


verse  ranges  form  the  extensive  peninsulas  which  so  greatly  enrich 
the  contours,  both  of  Asia  and  Europe. 

Examples  of  this  direction  are  found  in  the  Ural  and  Suliman  Mountains,  and 
the  Ghauts  of  India ;  in  the  Great  Kinghan,  and  the  chains  which  fill  the  peninsulas 
of  Kamchatka.  Corea,  and  Indo-China ;  and  in  the  mountains  of  the  Hellenic  pe- 
peninsula,  of  Italy,  and  of  Scandinavia. 

3.  In  Africa  the  two  directions  occur,  but  without  intersection, 
each  controlling  a  separate  division  of  the  continent ;  and  in  Aus- 
tralia the  north-south  direction  exists  alone.  Hence  these  two 
continents  show  a  simplicity  and  unity  of  structure  similar  to  that 
of  the  New  World. 

The  great  chains  of  islands  skirting  the  eastern  shores  of  Asia,  belong  to  the 
north-south  chains  of  upheaval,  and   those  between  Asia  and  Australia  mainly  to 


3.  In  Africa  the  greatest  heights  of  the  main  axis  lie  in  the 
vicinity  of  the  equator,  in  the  plateau  and  mountains  of  Abyssinia, 
at  the  junction  of  the  east-west  and  north-south  swells.  The  vol- 
canic peaks  of  Kenia,  Kilima-Njaro  and  Ngai,  and  the  Cameroons, 
are  also  in  the  equatorial  regions. 

The  secondary  axis  attains  its  greatest  elevation,  volcanoes  ex- 
cepted, in  the  plateaus  and  mountains  near  the  tropic  of  Capricorn. 

In  Australia  the  general  surface  of  the  land  seems  to  descend 
southward  ;  but  the  main  axis  attains  its  greatest  elevation  in  the 
Australian  Alps. 

The  following  tables  of  altitudes  exhibit  the  above  law. 
They  show  that  the  two  Americas  form  one  series  of  elevations  in- 


NORTH     AMERICA. 


CENTRAL   AMERICA 


ALASKA 


British  America 
St.  Elias 


Mexico. 


V    HJamin 


United  States, 

Mt.  Murchison       Gray's  Pk.          Pike's  Pk  Orizaba 

!                            !        !  Hat.  of  I 

Plains  of       1                          A        1  MexBco 

Columbia.       |  § 


Chimborazo 

Colombia     I 


V.  del  i'uego 
1 


SOUTH     AMERICA. 

N.  de  Sorata 

Hatlof  BolrJbt 


Aconcagua. 


Chili. 


25.000 
InjgUt 

20 
IE 


— -_-i\ 


FIG.    15.      THE   NEW    WORLD    FROM   NORTH   TO   SOUTH. 


the  east-west,  though  llie  two  intersect  in  Borneo  and  Celebes.  The  Greater 
Antilles,  between  ^lorth  and  South  America,  show  the  east-west  direction  of  up- 
heaval ;  and  the  Lesser  Antilles,  the  north-south  direction. 


V.  Position  of  Maximum  Altitudes- 

The  altitudes,  both  of  mass  elevations  and  of  mountains,  gradually 
increase  along  the  axes  of  the  continents,  to  a  maximum  which  is 
placed  towards  one  end  of  the  axis.  Hence  the  axes  themselves 
have,  in  the  direction  of  their  length,  a  long,  gentle  slope,  and  a 
short,  abrupt  one. 

The  accompanying  profiles,  designed  to  illustrate  this  law,  show  the  elevation 
in  different  parts  of  the  main  axis,  in  the  New  World  and  in  Asia-Europe. 

1.  In  the  New  World  the  highest  lands,  both  plateaus  and 
mountains,    are   found   in   the   plateau   of    Bolivia,   around    Lake 


creasing  from  north  to  south,  interrupted  by  the  zone  of  fracture ; 
and  that  Europe  and  Asia  form  another  series,  increasing  from  west 
to  east,  interrupted  by  the  sunken  basins  of  the  Black  and  Caspian 
Seas.  Volcanoes,  being  but  accidents  in  the  general  relief,  are 
omitted,  except  when  they  owe  their  altitude  to  the  elevation  of  the 
base  on  which  they  rest. 

NEW  WORLD. 

NORTH    AMERICA WESTERN    HIGHLANDS. 


Plains  and  Plateaus.  Eng.  feet. 

Plains  of  Alaska 800 

Pelly  Banks,  Upper  Yukon  .  1,400 
Central  Plateau  of  B.  Columbia  2,000 
Great  Plains  of  the  Columbia  R.  2,000 
Great  Basin,  Utah  (average)  .  4,500 
Great  Salt  Lake 4,230 


Mountains.  Eng.  feet. 

Northern  Rocky  Mountains  .     4,000 
Mt.Murchison,  British  Columbia  14,431 

Mt.  Hood,  Oregon       .     .     .  .11,225 

Mt.  Shasta,  California    .     .  .  14,440 

Fremont  Peak,  Wyoming    .  .  13,576 

Gray's  Peak,  Colorado    .     .  .  14,295 


EUROPE. 


ASIA. 


Spain. 


Caucasus. 


Alps 


Himalaya  Mts. 


Hindoo  Koosh.  Plat,  of 
Pamir. 


Persia. 


FIG.    16.      THE  OLD    WORLD   FROM    WEST  TO  EAST 


Titicaca.  Excepting  the  break  in  Central  America,  the  heights 
increase  along  the  main  axes,  from  the  Arctic  shores  to  this 
plateau,  a  distance  of  7,500  miles,  while  the  line  of  descent  to  the 
Southern  Ocean  is  but  2,500  miles.     (See  Fig.  15,  above.) 

The  secondary  axes  of  the  two  continents  show  the  same  law. 
Each  is  highest  near  the  southern  extremity,  and  the  maximum  ele- 
vation in  the  southern  continent  is  greater  than  that  in  the  northern. 

2.  In  Asia-Europe  the  heights  increase  towards  the  east,  both 
in  the  main  and  the  secondary  axis.  The  former  attains  its  greatest 
altitude  at  Mount  Everest,  in  the  Himalayas,  the  highest  known 
mountain  on  the  globe  ;  and  the  latter,  in  the  western  part  of  the 
Thian  Shan  system.     (See  Fig.  16,  above.) 


Central  Plateau 
of  Thibet 


Colorado  Plateau  (average)     .     6,000 
Plateau  of  Mexico         "  ..  8,000 

City  of  Mexico 7*473' 

City  of  Toluea        .     .    K    .     .     8,818 


Pike's  Peak,  Colorado,  .  .  .  14,215 
Mt.  Whitney,  Sierra  Nevada  .  15,000 
Popocatepetl,  Mexico  .  .  .  17,784 
Orizaba,  Mexico 17,897 


SOUTH    AMERICA  —  ANDES. 


Plateau  Elevations. 

City  of  Bogota,  Columbia 
"     Quito,  Ecuador 
"     Cuzco,  Peru   . 

Lake  Titicaca,  Bolivia 

City  of  La  Paz,       " 
"     Potosi,        " 

Plat,  of  Catamarca,  Arg.  Rep. 

Valley  of  Tenuyan,  Chili    . 


Eng.  feift.    . 

,  -8,655 
,  9,520-,, 

,  11,500 

,  12,800 

,  12,230 

,  13,330 
12,000 
.  7,500 


Mountains. 

Tolima,  Columbia  .  .  . 
Cayambe,  Ecuador  .  . 
Chimborazo,  "... 
Nevado  de  Sorata,  Bolivia 

Illimani,  Bolivia 24,155 

Aconcagua,  Chili 22,422 

Yanteles,  Patagonia   ....     8,030 
Sarmiento,  Tierra  del  Fuego    .     6,910 


Eng.  feet. 

18,336 
19,386 
21,414 
25,000 


42 


LAWS   OF   RELIEF. 


OLD  WORLD. 


EUROPE    AND    ASIA  —  FROM    WEST    TO    EAST. 


Plateaus.  Eng.  feet. 

Plateau  of  Spain 2,300 

"  Bavaria       ....     1,800 

"  Asia  Minor     .     .     .     2,500 

"  Armenia     ....     5,000 

"  West  Iran,  Persia    .     4,000 

"  East  Iran,  Afghanistan  6,000 

"  Western  Thibet       .  16,000 

"  Eastern  Thibet   .     .  11,000 


Mountains. 

Pyrenees,  Pic  Ane'thou  . 
Alps,  Mt.  Blanc  .  .  . 
Caucasus,  Mt.  Elbourz  . 
Hindoo  Koosh  .... 
Karakorum  Chain,  Mt.  Dapsan 
Dhawalagiri,  Himalaya  Mts. 
Mt.  Everest,  "  " 

Chumalari,  Bhootan    .     .     . 


Eng.  feet. 

.  11,168 
,  15,780 

18,524 
20,000 
g  28,278 
26,861 
29,002 
23,944 


VI.  Maximum  Altitudes  in  Tropical  Regions. 

The  continental  reliefs,  as  a  whole,  begin  with  vast  low  plains 
about  the  arctic  circle,  and  increase  in  altitude  towards  the  equatorial 
regions. 

The  culminating  regions  of  the  New  World  extend  from  20°  north 
latitude  to  16°  south ;  those  of  the  Old  World  from  28°  north  lati- 
tude in  Asia,  to  5°  south  in  Africa. 

The  effect  of  this  law  is  to  temper  the  burning  heat  of  the 
tropical  regions,  and  give  them  a  variety  of  climate  not  otherwise 
belonging  to  them.  If  this  order  were  reversed,  and  the  elevations 
increased  towards  polar  latitudes  from  low  plains  at  the  equator, 
those  regions  of  the  globe  at  present  the  most  highly  civilized  would 
be  a  frozen  and  uninhabited  waste. 


VII.  Predominant  Relief  Form  of  Individual  Continents. 

In  general,  each  continent  has  one  dominant  form  of  relief ,  which 
gives  it  a  special  character,  exerting  a  powerful  influence  upon  its 
climate,  and  upon  its  functions  both  in  nature  and  in  human  history. 

The  Americas  are  the  continents  of  low  plains.  The  great  fertile 
basins  of  the  Mississippi,  the  Amazon,  and  other  mighty  rivers,  are 
the  most  valuable  and  characteristic  regions  of  these  continents. 

Africa  has  no  extended  low  plain,  but  is  filled  with  vast  table- 
lands. It  is  the  continent  of  plateaus,  inferior  in  moisture  and  veg- 
etation, superior  in  temperature  and  in  the  development  of  animal 
life. 

Europe,  in  its  western  and  most  important  half,  is  but  a  net-work 
of  mountain  chains,  without  high  or  extensive  plateaus.  It  is  the 
continent  of  mountains. 

Asia,  the  largest  continent,  is  the  full  type  of  all  the  others.  It 
has  all  the  forms  of  relief  on  the  grandest  scale,  in  nearly  equal 
proportions,  and  in  the  greatest  variety  of  combination.  In  the 
north  and  west  are  the  most  extensive  plains  of  the  earth ;  in  the 
centre,  the  highest  and  largest  plateaus;  and  in  the  south,  the 
loftiest  mountain  chains. 

VIII.  Summary. 

All  that  has  been  said  of  the  reliefs  of  the  globe  may  be  summed 
up  in  a  single  grand  law,  as  follows :  — 

All  the  long,  gentle  slopes  descend  towards  the  Atlantic  Ocean 
and  its  prolongation,  the  Arctic ;  while  all  the  short  and  rapid 
slopes  are  directed  towards  the  Pacific,  and  its  dependent,  the  Indian 
Ocean,  the  highest  lands  being  adjacent  to  the  shores  of  the  greatest 
oceans. 


IX.  Formation  of  Reliefs. 

These  general  laws  which  regulate  the  elevations  of  our  globe  seem 


to  indicate  a  common  geological  cause,  which  may,  perhaps, be  found 
in  the  gradual  cooling  of  our  planet. 

The  operation  of  this  cause  may  be  conceived  as   follows  :  — 

The  heated  interior  of  the  Earth  continues  to  cool  and  to  contract  through  the 
progress  of  ages,  while  the  hardened  outer  crust,  receiving  from  the  sun  an  amount 
of  heat  about  equal  to  that  which  it  radiates  into  space,  contracts  at  a  much 
slower  rate,  if  at  all. 

Thus,  in  time,  the  interior  becomes  too  small  for  the  crust,  which,  obeying  lie 
force  of  gravity,  collapses,  the  circumference  adjusting  itself  to  the  decreasing  vol- 
ume within.  Vast  areas  subside  with  the  shrinking  interior,  while  the  adjacent 
portions,  too  large  for  the  space  left  for  them  to  occupy,  are  forced  into  great  folds 
and  ridges  by  lateral  pressure. 

Upon  the  subsiding  areas  the  waters,  before  spread  over  the  entire  surface  of 
the  globe,  gather  together,  and  the  folded  and  uplifted  areas  are  left  more  or  less 
uncovered.  Thus  were  formed  the  great  basins  of  the  Atlantic,  Pacific,  and 
Indian  Ocean,  with  the  three  pairs  of  continents  upraised  between  them. 

Confirmation  of  this  view  of  the  cause  of  grand  upheavals  is  found  in  the  fact, 
pointed  out  by  Professor  Dana,  that  the  height  of  the  border  mountains  and 
plateaus  of  the  continents  is  proportioned  to  the  width  of  the  oceans  which 
bathe  their  bases. 

In  the  American  continents,  for  example,  the  high  chains  of  the  Sierra  Nevada 
and  Andes  Mountains  skirt  the  shores  of  the  Pacific,  the  greater  ocean  ;  and  near 
the  Atlantic  are  the  low  Appalachian  Mountains  and  Brazilian  plateau.  A  simi- 
lar arrangement  of  elevations  appears  in  the  other  continents  ;  while  the  interior 
of  all,  more  remote  from  the  upheaving  force,  remains  comparatively  depressed. 
Thus  is  explained  the  typical  structure  of  the  continents,  noticed  in  the  preceding 
sections  and  in  the  first  law  of  relief. 

The  almost  infinite  variety  of  inequalities  in  the  Earth's  surface,  therefore,  is 
subject  to  a  few  general  laws.  Here,  as  elsewhere,  everything  has  been  made 
with  order  and  in  due  measure,  and  doubtless  also  with  reference  to  a  final  aim 
which  science  seeks  to  discover  by  patient  and  intelligent  research. 


ANALYSIS  OF  SECTION  IX. 

I.  Typical  Structure  of  Continent*. 

1.  Law  Stated. 

2.  Examples. 

II.  Position  of  Main  Axis. 

1.  Law  Stated. 

2.  Examples. 

III.  Direction  of  Elevations. 

1.  Law  Stated. 

2.  Directions  Specified.    Examples. 

3.  Directions  Named. 

IV.  Contrasting  Plans  In  Old  and  New  World. 

1.  Law  Stated. 

2.  Effect  on  Structure  of  New  World. 

3.  Effect  on  Structure  of  Asia-Europe. 

4.  Effect  on  Structure  of  Africa. 

5.  Asiatic  Islands  how  formed.     Antilles. 

V.  Position  of  Maximum  Elevation  in  Continents. 

1.  Law  Stated. 

2.  Example  in  New  World. 

3.  Example  in  Asia-Europe. 

4.  Example  in  Africa. 

5.  Example   in  Australia. 

6.  Tables  op  Altitudes. 

VI.  Position  on  Globe  ol  Maximum  Elevations. 

1.  Law  Stated. 

2.  Culminating  Region  of  New  World.    Of  Old  World 
3    Effect  of  this  Law  on  Climates. 

VII.  Dominant  Relief  Form  of  Individual  Continents. 

1  Law  Stated. 

2.  Examples. 

a.  American  Continents. 

b.  Africa. 

c.  Europe. 

d.  Asia. 

VIII.  Summary  of  Law»  of  Relief. 
IX.  Formation  of  Reliefs. 

1.  Common  Cause  Underlying  Reliefs 

2  How  this  Cause  operates. 

3.  Confirmation  of  this  View. 

4.  Result  of  Operation  of  General  Causes. 


ISLANDS. 


43 


X.  — ISLANDS. 

I.  Extent  and  Classification. 

The  multitude   of   small  and  apparently  fragmentary  bodies  of 
land,  called   islands,  form    only  about  one- 
seventeenth  part  of  the  entire  land  surface 
of  the  globe. 

Figure  1 7  exhibits  this  proportion  to  the  eye.  The 
greatest  square  represents  the  surface  of  the  globe ; 
the  smaller  inclosed  squares  represent  the  areas  of  the 
continents  and  the  islands  ;  and  the  surrounding 
spare,  the  sea. 

Islands  are  of  two  classes,  Continental 
and  Oceanic  islands. 

II.  Continental  Islands. 

1.  Position.  Continental  islands  are  sit- 
uated in  the  immediate  vicinity  of  the  conti- 
nents, and  form  properly  a  part  of  the  conti- 
nental structure.  They  are  generally  elon- 
gated, and  occur  in  lines  parallel  to  the 
coasts,  like  the  Japan  Islands  and  the  West 
Indies  ;  or  they  form  a  continuation  of  the 
continental  mountain  chains,  like  the  long 
line  of  the  Sunda  Islands. 

2.  Character.  The  continental  islands  have  the  same  kinds  of 
rocks  and  mountain  forms,  and  the  same  varieties  of  plants  and  large 
animals,  which  are  found  on  the  neighboring  coasts  of  the  mainland. 

3.  The  Size  of  this  class  of  islands  varies  extremely.  Some  are 
mere  isolated 

rocks,  while  others 
occupy  large  areas, 
like  the  British 
Isles,  Japan  Isl- 
ands and  Mada- 
gascar; or,  more 
extensive  still,  Pa- 
pua and  Borneo, 
each  of  which  has 
an  area  exceeding 
200,000  square 
miles. 


WATER. 
144,000.000 

CONTINENTS. 
50,000,000. 

ISLANDS, 

j-    2,900,000. 

SURFACE   OF    THE   GLOBE,  196,000,000. 

FIG.    17.    RELATIVE  AREA   OF   LAND  AND   WATER  IN  ENGLISH 
SQUARE   MILES. 


III.    Oceanic 
anils. 


Isl- 


Whitsunday  island.     (See  Topic  IV.,  page  44.) 


1.  Distinctive 

(    ii  a  r  acter  . 

Oceanic  islands  lie 

at  a  distance  from 

the  continents,  in 

the  midst  of    the 

ocean  basins. 

They  are  always  small,  and,  though  sometimes  forming  lines,  or  bands, 

they  more  frequently  occur  in  groups. 

The  rocks  which  make  up  the  body  of  the  continents  and  conti- 
nental islands  —  sandstone,  slate,  granite,  and  the  various  metamor- 
phic1  rocks  —  are  entirely  wanting  in  oceanic  islands.      The  latter 

1  Rocks  which,  originally  formed  by  deposits  from  water,  have  since  undergone  more  or 
less  change,  and  have  become  crystalline. 


are  composed  either  of  volcanic  substances,  or  of  limestone.  Hence 
they  present  much  less  variety  in  relief  forms  than  the  continental 
islands. 

2.  Classes.  Navigators  distinguish  two  classes  of  oceanic 
islands,  —  the  high  and  the  low,  —  which 
correspond  to  two  natural  groups,  distinct  in 
form,  geological  character,  and  mode  of 
formation. 

The  high  islands  are  volcanic  cones,  with 
craters,  many  of  which  are  still  active.  The 
low  islands  are  the  emerged  tops  of  subma- 
rine coral  reefs. 

3.  Volcanic  Islands  are  more  or  less 
circular  in  outline  ;  are  usually  considerably 
elevated,  with  rapid  slopes  ;  and  are  of  mod- 
erate size.  Sometimes  two  or  more  volca- 
noes, clustered  together,  form  a  single  island 
of  larger  size  and  more  irregular  outline. 

Occasional  islands  rise  but  little  above  the 
surface  of  the  sea,  their  craters  being  filled 
by  sea  water.  This  is  the  case  in  Barren 
Island,  in  the  Bay  of  Bengal,  which  consists 
of  an  old  crater,  entered  by  a  single  passage 
from  the  sea,  with  a  more  recent  cone  of 
eruption  in  the  centre. 

Many,  however,  rise  to  Alpine  heights  —  like  the  peaks  of  Hawaii, 
in  the  Sandwich  Islands,  nearly  14,000  feet  in  elevation ;  Pico  de 
Teyde,  in  the  Canaries,  14,000  feet ;  and  Tahiti,  in   the  Society 

Islands,  over  7,000 
feet  above  the 
level  of  the  sea. 

Volcanic  islands 
occur  in  consider- 
able numbers  in 
the  two  great  vol- 
canic zones,2  as 
well  as  in  mid- 
ocean.  In  these 
zones  new  volcanic 
islands  appear 
from  time  to  time. 

In  the  southern  part 
of  the  Grecian  Archi- 
pelago  is  the  island  of 
Santorini,  in  form  re- 
sembling a  horseshoe, 
inclosing  a  bay  seven 
miles  long  by  five 
broad.  Within  this 
bay  are  four  volcanic 
islands,  three  of 
which  have  arisen 
within  the  last  300 
years,  the  latest  ap- 
pearing in  1866.  The  first  of  the  four  rose  about  200  years  before  the  Christian 
era.     These  new  islands  are  cones  of  eruption  formed  within  the  old  crater. 

In  some  cases  temporary  islands,  of  considerable  extent,  have  been  formed  by 
submarine  volcanic  eruptions ;  an  example  of  which  was  furnished  by  the  island 
of  Ferdinandia,  formed  near  the  south  coast  of  Sicily  in  1831.  A  submarine  vol- 
cano burst  forth  in  July,  and  raised  a  cone  of  eruption  to  the  height  of  200  feet 


2  See  page  15,  Section  IX.,  Topic  II.,  and  Map  of  Volcanoes,  pp.  18,  19. 


44 


ISLANDS. 


(I 


above  the  sea,  with  a  circumference  of  a  mile  and  a  quarter.  Before  the  end  of  the 
year  it  disappeared,  and  a  few  years  afterwards  the  water  on  its  site  was  200  feet 
deep. 

IV.  Coral  Islands. 

1.  General  Character.  Coral  islands  are  among  the  most 
striking  phenomena  of  the  tropical  seas. 

Whitsunday  Island,  in  Low  Archipelago,  in  the  midst  of  the 
Pacific,  may  serve  as  an  example  of  this  class.  Rising  but  a  few 
feet  above  the  surface  of  the  ocean  it  forms  a  narrow,  unbroken, 
nearly  circular  ring,  surrounding  a  central  lagoon  of  quiet  water. 

Approaching  it  from  the  windward  side,  the  voyager  perceives  first  a  line  of 
angry  surf  breaking  on  a  white  beach  of  coral  sand,  in  strong  contrast  with  the 
deep  blue  color  of  the  sea.  Behind  this  a  garland  of  luxuriant  vegetation,  whose 
tropical  beauty  is  enhanced  by  the  noble  cocoa-palm  encircles  the  quiet  waters 
of  the  lagoon,  while  all  around 
spreads  the  broad  blue  sea. 

The  island  of  Natupe,  in 
the  same  archipelago,  is  also 
unbroken,  but  is  more  elon- 
gated and  much  larger,  the 
longer  diameter  measuring 
nearly  twelve  miles. 

2.  Atolls.  The  usual 
form  of  coral  islands  is 
that  of  a  broken  ring, 
numerous  channels  af- 
fording entrance  into 
the  lagoon.  Such  a 
group  of  islands  is  called 
an  atoll,  a  Malay  term, 
which  has  been  adopted 
to  designate  these  sin- 
gular structures. 

The  central  lagoon  in- 
closed by  an  atoll,  is  in- 
variably shallow,  seldom 
exceeding  a  few  scores, 
or  at  most  hundreds,  of 
feet  in  depth  ;  while  the 
outer  sea  reaches  a  depth 
of  thousands  of  feet  at 
a  short  distance  from  the  shore,  showing  that  the  atoll  rests  upon  a 
submarine  mountain. 

Atolls  are  often  clustered  together  in  large  numbers,  forming 
extensive  archipelagoes.  Paumotu,  or  Low  Archipelago,  numbers 
eighty  coral  islands,  nearly  all  of  which  are  atolls ;  the  Caroline, 
Gilbert,  and  Marshall  islands  together  contain  eighty-four  atolls, 
while  the  Laccadive  and  Maldive  islands  form  two  long  double  series 
of  atolls  extending  800  miles  from  north  to  south. 

The  chief  of  the  Maldives  calls  himself  the  "  Sultan  of  the  Twelve  Thousand 
Isles ;  "  and  Admiral  Owen,  who  reports  the  fact,  says  that,  counting  the  single 
islands  in  the  atolls,  this  is  no  exaggeration. 

3.  Combination  of  Volcanic  and  Coral  Islands.  A  large 
number  of  volcanic  islands  in  the  Pacific  are  encircled  by  coral  reefs, 
which,  when  near  the  shore,  are  called  fringing  reefs.  When  at  a 
considerable  distance,  leaving  a  lagoon  of  quiet  water  between  them 
and  the  volcanic  island,  they  are  termed  barrier  reefs. 

Bolabola,  one  of  the  Society  Islands,  presents  a  striking  example  of  this  arrange- 
ment. From  its  volcanic  summit  the  eye  stretches  over  the  quiet  waters  of  the 
lagoon  to  the  outer  garland  of  green  islands  which  separate  it  from  the  surround- 
ing ocean,  beholding  a  scene  as  strange  as  it  is  beautiful.     Hogoleu,  in  the  Society 


FIG.    18.      CORAL   ISLANDS   OF   DIFFERENT   FORMS,  AND    BOLABOLA — MAP   AND   SECTION. 


Islands,  and  many  others  present  the  same  arrangement,  which  differs  from  an 
atoll  only  by  having  one  or  more  mountains  within  the  central  lagoon. 

In  Fig.  18  the  several  forms  of  coral  islands  are  seen.  Taiara  is  an  unbroken 
ring,  Henuake,  a  ring  with  a  single  passage  to  the  lagoon  ;  Bowditch  is  an  empty 
atoll ;  and  Bolabola,  a  volcanic  island  within  an  atoll.  The  section  of  Bolabola 
shows  the  encircling  reefs,  resting  on  the  slopes  of  the  volcanic  mountain. 

3.  Formation  of  Coral  Reefs.  Coral  reefs  are  masses  of 
limestone  originally  secreted,  in  the  form  of  coral,  by  minute  polyps 
which  live  in  countless  numbers  in  the  tropical  seas. 

The  structure  of  the  polyp  consists  of  a  cylindrical  or  sack-like  membrane, 
attached  at  the  bottom  to  some  solid  body,  and  inclosing  a  second  sack  which 
forms  the  stomach.  At  the  top  is  an  opening  or  mouth,  which  is  surrounded  by 
thread-like  organs  called  tentacles.  When  expanded,  the  polyp  resembles  a  flower 
in  form  and  often  in  the  beauty  of  its  color.  (See  Fig.  19,  page  45.)  The  solid 
coral,  which  composes  the  reef,  is  secreted  in  the  cavity  between  the  outer  and 
inner  membranes,  as  the  bones  are  secreted  in  the  bodies  of  higher  animals. 

Coral  polyps  multiply  by 
eggs,  to  a  certain  extent,  but 
chiefly  by  a  process  of  bud- 
ding similar  to  the  branching 
of  plants.  Thus  they  grow 
into  vast  communities,  in 
which  generation  succeeds 
generation,  each  individual 
leaving  behind,  as  it  dies,  its 
contribution  to  the  reef  in  the 
form  of  a  small  cell  of  carbon- 
ate of  lime.  Each  commu- 
nity had  its  origin  in  a  single 
free  polyp,  which  was  pro- 
duced from  an  egg,  and  sub- 
sequently attached  itself  to  the 
ground  at  the  proper  depth 
for  its  growth. 

The  coral  produced  by 
a  single  community  of 
polyps  grows  chiefly  up- 
ward ;  but  multitudes 
of  distinct  communities 
often  live  so  near  to- 
gether that  the  small 
lateral  growth  of  each 
brings  them  into  contact. 

Their  separate,  fragile 
structures,  gradually 
broken  up  and  compacted  by  various  means,  are  in  time  transformed 
into  a  solid  mass,  forming  walls  of  coral  rock  frequently  of  enormous 
extent.  The  great  barrier  reef  near  the  northeastern  shores  of 
Australia,  the  longest  known,  is  not  less  than  1,250  miles  in  length. 

Reef-building  polyps  do  not  live  below  the  depth  of  100  or  120 
feet,  and  hence  require  a  foundation  near  the  surface.  This  is  fur- 
nished by  submarine  mountains  and  plateaus,  or  the  slopes  of  those 
volcanic  cones  which  form  the  high  islands. 

Growing  vertically,  the  reefs  repeat  at  the  surface  the  outlines  of 
their  bases,  which  fact  gives  rise  to  the  circular  figure  both  of  atolls 
and  reefs  in  mid-ocean,  and  to  the  elongated,  wall-like  form  of  the 
reefs  adjacent  to  the  continents,  like  those  of  Florida  and  of  Australia. 

The  formation  of  fringing  reefs  can  readily  be  explained,  but  it  is  less  easy  to 
see  why  the  barrier  reefs  are  so  distant  from  the  islands  which  they  surround. 
This  is,  however,  satisfactorily  explained  by  Darwin,  who  has  ascertained  that  the 
base  of  these  reefs  often  reaches  1,000  or 'even  1,500  feet  in  depth,  while  it  is 
known  that  the  polyps  live  only  at  slight  depths. 

He  infers  that  they  were  originally  fringing  reefs,  and  that  their  foundations 
have  since  gradually  sunk.  During  such  a  slow  subsidence,  the  reef,  always  grow- 
ing towards  the  surface  of  the  sea,  preserves  its  position  ;  while  the  island  gradu- 
ally becomes  smaller,  and  the  lagoon  enlarges  proportionally.     Finally  the  island 


Bolabola. 


LAWS    OF  RELIEF. 


45 


may  entirely  disappear,  in  which  case  the  hairier  reef  becomes  an  atoll  with  an 
empty  lagoon  in  the  centre.  Dana's  extensive  observations  confirm  this  view. 

4.  Islands.  Though  the  polyps  perish  when  they  reach  the  sur- 
face of  the  sea,  yet  the  debris  of  the  disin- 
tegrating coral,  accumulated  by  the  waves 
upon  the  top  of  the  reef,  soon  raise  it  above 
the  tvater,  forming  the  soil  of  one  or 
more  islands.  Such  islands  are  never 
more  than  from  ten  to  twelve  feet  above 
the  sea,  the  limit  assigned  them  by  the 
power  of  the  waves.  They  are  usually 
higher  on  the  outer  margin,  sloping 
slightly  towards  the  lagoon. 

The  soil,  exposed  to  the  action  of  the 
atmosphere,  is  gradually  prepared  to 
support  vegetation,  which  presently 
makes  its  appearance.  Seeds  of  a  few 
plants,  which,  from  their  hardy  nature,  are  not  injured  by  sea  water, 
are  transported  by  the  waves  and  thrown  upon  the  shores,  while 
others  are  brought  by  birds.  Under  the  influence  of  a  moist  trop- 
ical climate  they  develope  and  multiply  with  rapidity,  and  soon  the 
entire  island  is  covered  with  luxuriant  verdure. 

Variety  is  wanting,  however,  as  the  whole  flora  consists  of  scarcely 
more  than  a  score  of  species.  Pandanus  trees,  and  the  majestic 
cocoa-palm,  are  the  most  characteristic  ornaments,  as  well  as  the 


FIG.  19.      LIV 


most  useful  representatives,  of  the  vegetable  kingdom  in  the  coral 
islands.  Thus,  however  full  of  beauty  and  interest  these  islands 
may  be,  they  offer  but  scanty  resources  for  man's  support. 

With  only  one  kind  of  rock  and  soil, 
and  no  metals  for  tools  ;  a  land  without 
mountains,  valleys,  or  rivers,  the  arable 
portion  of  which  is  only  a  small  part  of 
its  area  ;  with  a  flora  reduced  to  a  few 
species,  and  a  fauna  lacking  all  large  an- 
imals :  the  coral  islands  are  almost  des- 
titute of  means  for  that  higher  culture 
which  is  the  true  end  of  man's  existence. 
5.  Distribution  of  Corals.  Reef- 
building  polyps  are  confined  to  the  trop- 
ical seas,  where  the  winter  temperature 

is  not  below  68°  Fahr.     But  remains  of 
ing  coral.  coral  reefg  are  found  in  the  rockg  of  th& 

continents,  in  nearly  all  latitudes,  indicating  that,  in  geological  times, 
there  was  a  similarity  of  temperature  throughout  the  globe. 

Coral  formations  are  most  extensive  in  the  Pacific  Ocean,  espe- 
cially south  of  the  Equator  (see  map,  pages  18,  19) ;  and  in  the  two 
great  archipelagoes  of  the  East  and  West  Indies  ;  but  a  large  num- 
ber of  coral  islands  also  occur  in  the  Indian  Ocean.  The  Coral 
Sea,  east  of  northern  Australia,  is  particularly  remarkable  for  the 
great  extent  of  its  coral  reefs. 


ANALYSIS  OF  SECTION  X. 

I.  Extent  and  Classes  of  Islands. 
II.  Continental  Islands. 

1.  Position. 

a.  With  reference  to  continents 

b.  Arrangement. 

c.  Examples. 

2.  Charactee. 

3.  Size. 

III.  Oceanic  Islands. 

1.  Distinguishing  Chaeactseistk-s. 

a.  Position. 

b.  Size  and  arrangement. 

c.  Rocks  and  soil. 

2.  Classes. 

a.  High  islands. 

b.  Low  islands. 
3   Volcanic  Islands. 

a.  Form  and  size. 

b.  Elevation. 

c.  New  islands. 

d.  Temporary  island. 

IV.  Coral  Islands. 

1.  General  Chaeactee. 

a.  Examples  In  Whitsunday  and  Natnpe. 

b.  Atolls.    Form.     Central  lagoons.     Archipelagoes. 

2.  Combination  op  Coral  and  Volcanic  Islands     Examples. 

3.  Formation  of  Bun. 

a   Origin  of  reef. 

Structure  and  secretion. 
Mode  of  multiplication. 
Result  of  budding  process. 
Origin  of  communities 

c.  Mode  of  production  of  reefs 
d    Foundation  of  reefs. 

e.  Origin  of  barrier  reefs  and  atolls. 
f.  Islands  feom  Coeal  Reefs. 

a    How  produced. 

b.  Elevation. 

c.  Vegetation. 

d.  Adaptation  of  coral  islands  to  man's  support  and  progress. 
5.  Distribution  of  Corals. 

a.  Present  limits. 

b.  Distribution  in  geological  times. 

c.  Retcions  of  most  extensive  formations. 


b    Polyps. 


QUESTIONS. 

1.  Continental  Islands.    (See  Map  of  the  World,  pages  28,  29.) 

How  do  the  opposite  shores  of  the  Pacific  Ocean  compare  in  the  number  and  size  of 
their  islands? 

What  islands  form  properly  a  continuation  of  Aliaska  peninsula? 

What  islands  form  a  continuation  of  the  peninsula  of  Kamchatka? 

What  three  great  islands  form  a  chain  nearly  parallel  to  the  coast  of  Manchuria? 

What  islands  east  of  China? 

What  islands  east  and  southeast  of  Indo-China? 

What  islands  form  a  chain  extending  from  the  Malay  peninsula  nearly  to  Australia  ? 

What  islands,  and  groups  of  islands,  form  a  chain  nearly  parallel  to  the  northeastern  coasts 
of  Australia? 

What  large  islands  nearly  parallel  to  the  southeastern  coasts  of  Australia? 

To  what  class  do  these  various  islands,  and  groups  of  islands,  belong  ? 

Why  are  they  to  be  regarded  as  continental  islands? 

What  archipelago  between  North  and  South  America? 

What  continental  islands  on  the  opposite  shores  of  the  north  Atlantic? 

In  what  part  of  the  Arctic  Ocean  are  islands  most  numerous  ? 

What  is  the  most  extensive  of  the  Arctic  lands? 

What  large  island  west  of  the  northern  projection  of  Asia? 

Of  what  mountain  system  is  NovaiaZemliaa  continuation? 

What  large  continental  island  off  the  eastern  coast  of  Africa? 

Which  ocean  has  the  largest  and  most  numerous  continental  islands  ? 

2.  Oceanic  Islands.     (See  Map,  pages  18,  19.) 

In  what  part  of  the  Pacific  are  oceanic  islands  the  most  numerous? 
Of  how  many  classes  are  oceanic  islands? 

What,  commencing  with  the  most  westerly,  are  the  principal  groups  of  coral  islands  north 
of  the  Equator?     South  of  the  Equator? 
In  what  groups  are  volcanic  and  coral  islands  combined? 
What  parallel  and  meridian  cross  the  volcanic  group  of  the  Sandwich  Islands? 
Between  what  parallels  and  meridians  are  most  of  the  coral  islands  of  the  Pacific  situated? 
What  two  groups  of  coral  islands  in  the  western  part  of  the  Atlantic? 
What  is  the  character  of  most  of  the  islands  in  the  Lesser  Antilles  ? 
What  two  volcanic  islands  lie  east  of  Greenland  ? 
What  clusters  of  islands  off  the  west  coast  of  Africa? 
To  what  class  do  these  islands  belong  ? 

What  volcanic  islands  in  the  northeastern  part  of  the  Indian  Ocean  ? 
What  group  of  coral  islands  south  of  Barren  island  ? 

What  three  groups  of  coral  islands  in  the  central  part  of  the  Indian  Ocean? 
ITow  are  these  groups  situated  in  respect  to  each  other? 
What  other  coral  islands  in  the  Indian  Ocean  ? 
What  volcanic  islands  near  Madagascar  ? 


46 


REVIEW. 


Note. 
refer. 


REVIEW  OF  PARTS  I.  AND  II. 

-The  Roman  numerals  indicate  the  sections,  and  the  Arabic  the  pages,  to  which  the  questions 


PART  I. 


I.  Name  and  define  the  two  main  divisions  of  the  geography  of  nature.  What  problems  does 
physical  geography  investigate?     How  does  physical  geography  differ  from  geology? 

II.  What  is  the  extent  of  the  solar  system?  How  long  is  a  ray  of  light  from  the  Sun  in 
reaching  the  planet  Neptune. 

III.  What  motions  are  common  to  all  the  planets?  What  is  the  position  of  the  axes  of  the 
planets  in  respect  to  the  planes  of  their  orbits?  To  what  degree  is  the  Earth's  axis  inclined? 
What  is  the  effect  of  the  inclination  of  the  planetary  axis? 

IV.  What  is  the  specific  gravity  of  the  Earth  ? 

V.  How  would  you  ascertain  the  difference  in  the  longitude  of  two  places,  the  difference  in 
time  being  known  ?     What  is  the  reason  of  this  relation  of  longitude  to  time  ? 

VI.  What  property  belonging  to  magnets  is  exhibited  by  the  Earth?  What  is  magnetic 
declination.  What  is  the  direction  of  declination  in  the  Atlantic  Ocean  ?  What  is  the  direc- 
tion in  the  Pacific? 

VII.  What  evidences  are  there  of  a  high  temperature  within  the  Earth?  Explain  the  forma- 
tion of  the  geysers.  State  the  result  of  observations  on  the  Earth's  internal  temperature. 
How  are  volcanic  mountains  formed? 

VIII.  How  does  the  activity  of  volcanoes  vary  at  different  periods?  What  are  the  premoni- 
tions of  a  volcanic  eruption  ?  When  was  the  first  eruption  of  Vesuvius  in  historic  times,  and 
what  was  its  result  ?    How  do  the  eruptions  of  some  of  the  most  famous  volcanoes  vary  ? 

IX.  Describe  the  general  distribution  of  volcanoes.  Where  are  the  two  great  volcanic  zones 
situated?  In  what  particular  regions  is  volcanic  activity  most  intense ?  What  is  the  primary 
source  of  volcanic  action?  How  are  volcanic  phenomena  related  to  the  upheaval  of  mountain 
chains  ? 

X.  What  are  earthquakes ?  What  are  the  different  classes  of  earthquake  movement?  With 
what  velocity  does  the  earthquake  wave  move?  Where  are  the  most  extensive  earthquake 
areas?  In  what  part  of  the  year  are  earthquakes  most  frequent?  What  general  cause  may  be 
supposed  to  occasion  earthquakes  ? 

PART  II. 

I.  (21.)  What  are  the  several  geographical  elements  of  the  globe? 

How  are  the  form  and  arrangement  of  the  land  masses  connected  with  organic  life  ? 

What  is  the  effect  of  diversity  in  the  size  and  position  of  the  land  masses? 

Describe  the  arrangement  of  the  land  masses  upon  the  globe. 

What  is  the  number  of  the  continents;  and  what  contrast  observed  in  their  position? 

What  contrast  presented  in  the  positions  of  the  three  pairs  of  continents  ? 

WThat  farther  contrast  in  the  position  of  the  lands  and  the  sea. 

(22)  What  are  the  relative  positions  and  areas  of  the  land  masses? 

Enumerate  the  topics  discussed  in  Section  I.,  with  the  principal  divisions  of  each. 

II.  Under  what  two  aspects  are  the  continent*  to  be  studied? 
What  is  the  fundamental  figure  of  all  the  continents  ? 

What  is  the  direction  of  the  greatest  elongation  of  the  several  continents? 
What  is  the  effect  of  the  difference  in  the  direction  of  elongation  ? 
What  importance  is  attached  to  irregularities  in  the  outline  of  continents  ? 
(23.)  What  coincidence  is  observed  between  the  relative  indentation  of  the  coasts,  and  the 
comparative  civilization  of  the  continents? 

How  do  the  several  continents  compare  in  the  amount  of  indentation  of  their  coasts? 
Enumerate  the  topics  and  sub-topics  of  Section  II. 

III.  (24.)  What  is  the  relief  of  a  continent,  and  how  does  it  differ  from  altitude? 
What  are  the  several  forms  of  relief? 

What  importance  attaches  to  the  study  of  relief  forms? 

Describe  the  position  of  some  of  the  most  extensive  plains. 

What  classification  is  based  on  the  surface  of  plains? 

Define  each  class  and  give  examples. 

How  are  different  treeless  plains  designated? 

(25.)  How  do  the  different  classes  of  plains  compare  in  fertility? 

Mention  some  of  the  most  celebrated  alluvial  plains. 

What  is  the  comparative  altitude  of  the  several  classes  of  plains? 

Enumerate  the  topies  discussed  in  Section  III.,  with  the  several  divisions  of  each. 

IV.  How  are  plateaus  situated?    Examples. 

What  is  the  elevation  of  the  several  orders  of  plateaus  ? 

(26.)  What  is  the  importance  of  plateaus  in  the  continental  reliefs? 

What  is  the  usual  character  of  their  surface  and  soil  ? 

What  is  the  form  of  a  mountain  chain? 

To  what  extent  is  the  summit  indented? 

How  are  mountain  chains  supposed  to  have  been  formed? 

How  are  they  classified  ?    Examples. 

(27.)  What  are  the  distinguishing  features  of  each  class? 

How  are  valleys  among  mountain  ranges  distinguished  ? 

How  do  the  valleys  differ  in  the  two  classes  of  mountain  systems? 

What  is  the  origin  of  valleys  in  plains?    Describe  their  formation. 

(30.)  What  features  of  relief  have  all  the  continents  in  common? 

What  gives  the  continents  their  common  tendency  to  a  triangular  form  ? 


What  determines  their  individual  figures  and  contours? 

Enumerate  the  topics  discussed  in  Section  IV.,  with  the  primary  divisions  of  each. 

V.  (31.)  How  do  the  two  continents  of  the  New  World  compare  in  structure  ? 
Describe  the  position,  extent,  and  structure  of  the  primary  highlands  of  North  America. 
How  does  the  elevation  of  the  plateau  vary,  from  North  to  South  ? 

What  is  the  position,  structure,  and  altitude  of  the  Rocky  Mountains? 

Describe  the  Sierra  Nevada  and  the  Cascade  Mountains. 

What  is  the  position  and  structure  of  the  Atlantic  highlands  ? 

What  is  the  altitude  of  the  Appalachian  system  of  mountains  ? 

(32.)  What  is  the  character  of  the  central  region  of  North  America? 

What  are  the  distinguishing  features  of  South  America  ? 

How  do  these  several  features  compare  with  the  corresponding  regions  in  North  America? 

Describe  the  primary  highland  of  South  America,  giving  its  structure,  altitude,  and  slopes. 

Describe  the  secondary  highland.     (33. )  What  is  the  character  of  the  central  region  ? 

Enumerate  the  topics  discussed  in  Section  V,  with  their  primary  and  secondary  divisions. 

VI.  In  what  respect  does  Asia-Europe  resemble  the  New  World  ? 
In  what  respects  is  the  structure  of  the  two  continents  similar? 
What  are  the  especial  characteristics  of  Asia  ? 

Describe  the  primary  highland  of  eastern  Asia,  giving  its  position,  structure,  and  altitude. 

Describe  the  secondary  highland. 

(34.)  How  are  the  two  highland  regions  connected  ? 

Describe  the  central  depression  of  eastern  Asia. 

What  is  the  character  of  the  northern  slope?    Of  the  eastern  slope? 

Describe  the  southern  slope,  its  plains  and  peninsulas. 

Describe  the  two  highland  regions  of  western  Asia. 

(35.)  Describe  the  central  region.    What  depressions  adjacent  to  the  plateau  of  Iran. 

What  is  the  character  and  surface  of  Arabia  ? 

Enumerate  the  topics  discussed  in  Section  VI.,  with  their  primary  and  secondary  divisions. 

VII.  How  is  the  continent  of  Europe  characterized  ? 

What  is  the  character  and  structure  of  its  primary  highland  ? 

(36.)  Describe  the  secondary  highland  region. 

Of  what  does  the  central  region  consist,  and  what  is  the  peculiarity  of  its  structure? 

What  are  the  main  divisions  of  High  Europe,  and  what  the  structure  of  each? 

Describe  the  structure  of  the  southern  peninsulas. 

In  what  respects  do  they  resemble,  and  in  what  differ  from,  the  peninsulas  of  Asia? 

What  is  the  extent  and  surface  of  the  great  European  plain  ? 

(38.)  What  are  the  surroundings  of  Low  Europe? 

Describe  the  Scandinavian  peninsula. 

How  are  the  British  Isles  connected  with  the  continent? 

How  do  the  subdivisions  of  Europe  compare  with  those  of  Asia  ? 

What  remarkable  contrasts  in  structure  presented  by  High  and  Low  Europe  ? 

Enumerate  the  topics  discussed  in  Section  VII.,  with  their  several  divisions. 

VIII.  What  are  the  characteristics  of  the  structure  of  Africa? 
How  are  the  two  halves  of  the  continent  united? 

Describe  the  primary  highlands  of  South  Africa. 

(39.)  Describe  the  secondary  highland,  and  the  central  region. 

What  are  the  highland  regions  of  North  Africa  ? 

What  remarkable  depressions  in  northern  and  eastern  Africa  ? 

Describe  the  central  region  of  northern  Africa. 

What  is  the  general  plan  of  structure  in  Australia? 

Describe  the  primary  highland  region.     What  forms  the  secondary  highland  region  ? 

Describe  the  central  depression. 

(40.)  Enumerate  the  topics  discussed  in  Section  VIII.,  with  their  subdivisions. 

IX.  Repeat,  in  their  order,  the  eight  general  laws  of  continental  relief. 
What  continents  most  clearly  illustrate  the  first  law? 

Give  examples  of  the  position  of  the  main  axis,  as  expressed  in  the  second  law. 

Describe  the  directions  of  elevations,  indicated  in  the  third  law,  and  give  examples. 

How  is  the  fourth  law  exhibited  in  the  structure  of  the  New  World  ? 

How  does  it  appear  in  the  structure  of  the  several  continents  of  the  Old  World  ? 

(41.)  How  is  the  fifth  law  exhibited  in  the  several  continents? 

(42.)  How  does  the  sixth  law  affect  the  climates  of  the  globe? 

How  is  the  seventh  law  expressed  in  the  several  continents? 

How  are  the  continents  supposed  to  have  been  uplifted? 

What  confirmation  of  this  view  appears  in  their  structure  ? 

X.  (43.)  What  proportion  of  the  land  surface  of  the  globe  consists  of  islands? 
What  is  the  position,  character,  and  size  of  the  continental  islands? 

In  what  respects  do  the  oceanic  islands  differ  from  the  continental? 

How  are  oceanic  islands  classified? 

What  is  the  size,  altitude,  and  position  of  the  volcanic  islands? 

Give  examples  of  the  recent  formation  of  volcanic  islands. 

(44.)  What  is  the  most  common  form  of  coral  islands? 

Give  examples  of  the  combination  of  volcanic  and  coral  islands. 

Describe  the  formation  of  coral  reefs. 

How  is  the  reef  converted  into  an  island? 

What  is  the  comparative  value  of  the  coral  islands  to  man  ? 

Describe  the  distribution  of  corals. 

Enumerate  the  topics  discussed  in  Section  X.,  with  their  primary  and  secondary  divisions. 


PART    III. 
THE    WATERS. 


INTRODUCTION. 

1.  The  second  great  geographical  element  to  be  con- 
sidered is  water,  which,  by  disintegrating  and  rearranging  the 
materials  of  the  Earth's  crust,  was  the  principal  agent  in  shaping 
what  is  now  the  solid  land.  It  is  equally  indispensable  in  carry- 
ing on  the  processes  of  vegetable  and  animal  life,  as  it  forms  the 
larger  part  of  all  organized  bodies. 

Water  is  a  liquid,  composed  of  two  gases,  oxygen  and  hydro- 
gen, not  simply  mixed  like  the  gases  composing  the  atmosphere,  but 
chemically  combined  in  the  ratio,  by  weight,  of  eight  to  one. 

Water  contracts  in  volume, 
with  a  diminution  of  its  tem- 
perature, until  reduced  to 
39.2°  Fahr.,  where  its  density 
is  greatest.  Below  this  tem- 
perature it  expands,  and  the 
formation  of  ice  crystals  soon 
commences,  the  freezing  point 
being  32°  Fahr. 

On  account  of  the  expansion 
below  39°.2,  the  water  near 
the  freezing  point  floats  on 
the  surface  of  ponds  and  lakes, 
and  ice  forms  there  rather 
than  in  the  depths.  The 
coating  of  ice,  even  though 
quite  thin,  tends  to  preserve 
the  warmth  of  the  water  be- 
neath, thus  limiting  the  ex- 
tent of  the  congelation. 

Did  water  continue  to  con- 
tract as  long  as  the  temperature  is  reduced,  like  other  substances 
in  nature,  the  freezing  particles,  being  heaviest,  would  sink  to  the 
bottom  ;  and  the  whole,  brought  successively  in  contact  with  the 
frosty  atmosphere  at  the  surface,  would  be  rapidly  frozen.  Thus, 
in  severe  winters,  the  great  lakes  of  middle  latitudes  might  be  con- 
verted into  vast  reservoirs  of  solid  ice,  which  no  summer's  sun  would 
have  power  to  melt. 

This  remarkable  exception  to  a  law  otherwise  universal  is,  there- 
fore, a  means  of  preserving,  in  cold  climates,  the  liquid  form  of  this 
element,  whose  ceaseless  circulation  is  one  of  the  primary  conditions 
of  the  existence  of  organic  life  upon  the  globe. 

2.  The  great  reservoir  of  terrestrial  waters  is  the  sea.  By 
slow  but  constant  evaporation  the  water  is  lifted  into  the  atmosphere 


HEAD  WATERS  OF  THE  APURIMAC —  ONE  OF  THE  SOURCES  OF  THE  AMAZOS. 


in  the  form  of  vapor,  which,  borne  by  the  winds  to  the  continents, 
is  there  condensed  and  falls  in  beneficent  rains. 

3.  The  rain  water,  spread  over  the  surface  of  the  continents, 
in  part  evaporates  again,  or  is  absorbed  by  vegetation  ;  and  a  part 
sinks  into  the  ground  through  the  porous  or  broken  strata,  reappear- 
ing at  the  surface  in  springs,  or  collecting  in  underground  streams 
and  quiet  subterranean  sheets  of  water. 

But  a  considerable  portion  flows  over  the  surface  in  brooks  and 
rivulets,  and  .these  uniting  with  the  streams  sent  forth  by  the  springs, 
convert  the  depressions  of  the  continents  into  lakes,  and  form  those 
mighty  rivers  which  return  the  surplus  water  to  the  sea  whence  it 

came.  Thus  is  produced  a 
vast  multitude  of  streams 
which,  like  the  arteries  of  the 
human  system,  carry  the  life- 
giving  element  to  all  parts  of 
the  continents. 

4.  Diverse  Conditions  op 
Terrestrial  Waters.  In 
this  ceaseless  circulation  the 
waters  of  the  Earth  appear 
under  three  different  condi- 
tions, each  governed  by  its 
own  special  laws,  and  re- 
quiring to  be  investigated  sep- 
arately, namely:  oceanic,  at- 
mospheric, and  continental 
waters.  The  last,  on  account 
of  their  immediate  dependence 
upon  the  reliefs  of.  the  land, 
must  be  studied  in  connection 
with  the  continental  struct- 
ures, by  means  of  which,  alone,  they  are  made  intelligible. 

ANALYSIS. 

Introduction. 

1.  Second  Geographical  Element. 

a.  Its  importance  in  geological  times. 

b.  Its  relation  to  organic  life. 

c.  Composition  of  water. 

d.  Effect  of  reducing  the  temperatnre. 

e.  Effect  of  expansion  at  low  temperature. 

2.  Reservoir  of  Terrestrial  Waters. 

Means  of  transportation  to  continents. 

3.  Rain  Waters. 

a.  Portions  removed  from  surface. 

b.  Portions  remaining  on  surface. 

4.  Diverse  Conditions  of  Terrestrial  Waters. 

a.  Several  conditions  enumerated. 

b.  Study  of  continental  waters. 


48 


RIVERS. 


CONTINENTAL  WATERS. 

I.  — RIVERS. 

I.  Sources  and  Systems  of  Rivers. 

1.  Sources  op  Rivers.  Springs,  which  form  the  remote  sources 
of  most  rivers,  are  the  outflow  of  percolating  waters  accumulated 
beneath  the  surface  of  the  ground. 

The  quantity  of  water  in  the  springs  varies,  from  a  tiny  streamlet 
trickling  from  crevices  in  the  rocks, 
to  a  stream  several  yards  broad, 
and  powerful  enough  to  turn  a  mill 
wheel.  The  most  copious  springs 
usually  occur  in  limestone  regions, 
where  extensive  subterranean  cavi- 
ties or  channels  favor  the  conflu- 
ence of  the  water,  so  that  it  forms 
considerable  streams  before  reach- 
ing the  surface. 

Some  springs  have  a  constant 
and  nearly  uniform  flow  throughout 
the  year,  showing  that  they  derive 
their  waters  from  some  place  be- 
yond the  influence  of  the  changing 
seasons  ;  while  others  diminish 
greatly,  or  cease  entirely,  in  times 

of  drought.  Some  are  intermittent,  having  regular  periods  of  rest 
which  vary  in  duration,  in  different  springs,  from  a  few  minutes  to 
several  days  or  weeks. 

The  commonly  received  explanation  of  intermittent  springs  supposes  a  subter- 
ranean cavity  (as  at  A,  Fig.  20),  with  one  or  more  fissures  (a,  6,  c,  d)  admitting 
water,  and  another,  in  the  form  of  a  siphon,  discharging  it. 

As  soon  as  the  reservoir  is  filled  up  to 
the  line  B  C,  the  level  of  the  highest  point 
in  the  siphon,  the  latter  begins  to  discharge 
the  water.  The  outflow  continues  until  the 
reservoir  is  emptied  to  the  line  D  E,  the 
level  of  the  place  of  exit,  when  it  ceases,  to 
recommence  as  soon  as  the  feeders  have 
again  brought  the  water  to  the  level  B  C. 

It  is  evident  that  the  conditions  sup- 
posed do  not,  of  necessity,  give  rise  to  an 
intermittent  spring ;  for  if  the  rate  of  in- 
flux at  all  times  equals,  or  exceeds,  that  of 
discharge,  the  water  cannot  fall  to  the  level 
D  E,  and  the  outflow  will  be  continuous. 

Springs  are  most  numerous  in  and 
around  mountainous  regions,  where 
their  formation  is  favored  by  a  va- 
riety of  causes.  More  rain  falls  up- 
on mountains  than  upon  either  pla- 
teaus or  plains  in  a  corresponding  po- 
sition ;  and  an  additional  supply  of 
water  is  derived  from  clouds  and  fogs 
which  frequently  hang  about  the 
mountain  tops,  even  when  the  lower 
lands  are  bathed  in  sunlight. 

Again,  the  broken  and  inclined 
strata,  in  mountainous  regions,  favor  the  entrance  of  the  surface 
water  into  the  ground,  furnish  channels  for  its  circulation  beneath 
the  surface,  and  facilitate  its  issue  at  lower  levels. 

The  temperature  of  springs  whose  waters  circulate  near  the  sur- 
face of  the  ground  varies  with  the  seasons  ;  those  from  a  depth  below 


the  level  of  constant  temperature  (see  page  11,  Topic  III.)  preserve 
throughout  the  year  the  mean  annual  temperature  of  the  place  where 
they  occur  ;  while  those  circulating  at  great  depths  are  thermal. 
•  2.  Formation  of  River  Systems.  Since  water  flows  from  the 
higher  to  the  lower  lands,  the  line  of  lowest  level  in  any  given  region, 
naturally  becomes  the  channel  of  the  main  river  in  that  region.  Nu- 
merous streams  from  the  surrounding  slopes  frequently  find  their 
way  to  the  sea  through  one  main  central  channel,  forming  a  river 
system,  which  takes  the  name  of  its  main  stream.  Thus  the  Missis- 
sippi system  is  composed  of  streams 
converging  from  the  west,  north, 
east,  and  intermediate  directions, 
and  uniting  in  the  central  valley  in 
which  the  Mississippi  itself  flows. 

The  area  drained  by  a  river  is 
called  its  basin.  The  line  of  sep- 
aration between  adjacent  basins, 
from  which  the  streams  flow  away 
in  opposite  directions,  is  called  the 
water-shed  (from  the  German  was- 
ser,  water,  and  scheide,  a  place  of 
separation). 

3.  The  AMOUNT  OF  WATER 
transported  by  a  stream  is  by  no 
means  proportionate  to  the  extent 
of  its  basin,  nor  to  the  length  of  its 
course,  but  depends  on  the  amount  of  rain  falling  upon  the  area 
drained,  and  the  ratio  of  evaporation  to  rainfall  throughout  the  ba- 
sin. Extensive  forests  in  a  river  basin  augment  the  volume  of  the 
water,  for  they  both  increase  the  rainfall  and  retard  the  evaporation 
of  water  from  the  soil.     (See  page  85,  Topic  II.,  2.) 

4.  Agency  of  Rivers.  Rivers 
are  active  and  powerful  agents  in 
the  Avork  of  erosion,  reconstruction, 
and  general  leveling,  which  is  con- 
stantly taking  place  on  the  surface 
of  the  continents.  The  modes  of  ac- 
tion, however,  vary  materially  in 
different  parts  of  the  course. 


FOHMATION    OF    INTKHMITTKNT    SPHINGS. 


a.    Windings  of  present  river-bed.     b.  c.    Parts  of  ancient  be//. 
FIG.   21.      THE   MISSISSIPPI   VALLEY    AT.  VICKSBURG. 


a.   Diluvial  sand  and  clay.     b.    Tertiary  strata,     c.    Cretaceous  rocks. 
FIG.   22.      SECTION  OF  THE   MISSISSIPPI   VALLEY   AT    VICKSBUKG 


II.  Erosion. 

1.  In  the  upper  COURSE  the  ero- 
sion, or  wear  cf  the  channel  by  the 
current,  is  chiefly  at  the  bottom  of 
the  stream.  Especially  is  this  the 
case  where  a  strong  slope  increases 
the  velocity  and  power  of  the  cur- 
rent, as  on  the  sides  of  mountains. 
The  valley  excavated  is  often  of 
great  depth,  but  narrow,  with  sides 
sloping  considerably,  sometimes 
even  precipitous. 

When  the  underlying  rocks,  in 
different  parts  of  the  course,  are  of 
unequal  hardness,  the  erosion  is  necessarily  unequal.  The  softer 
beds,  successively  traversed  in  descending  the  slope,  are  worn  more 
rapidly  than  the  harder  ones,  so  that  the  latter  become  the  heads  of 
precipices.  When  the  difference  of  level  between  two  successive 
hard  strata  is  great,  the  precipices  may  be  of  enormous  height,  the 


intervening  softer  strata  being  sometimes  entirely  cut  through  by  the 
falling  waters. 

2.  In  the  middle  AND  LOWER  course  the  stream  erodes  little  at 
the  bottom  but  more  at  the  sides,  undermining  its  bluffs  and  con- 
stantly widening  its  valley,  especially  during  freshets,  when  the  vol- 
ume and  velocity  of  the  water  are  greatly  increased.  The  debris  of 
the  eroded  banks  are  spread  over  the  bottom  of  the  valley,  and  upon 
inundated  lands,  or  borne  onward  to  the  mouth  of  the  stream. 

These  lateral  erosions  form,  in  process  of  time,  a  broad  bottom 
land  which  is  more  or  less  inundated  in  time  of  high  water,  and 
through  which,  in  low  water,  the  stream  flows  in  a  winding  course. 
The  sediment  of  the  inundating  waters,  accumulated  year  after  year, 
gradually  forms  the  rich  alluvial  soil  which  distinguishes  all  bottom 
lands. 

The  valley  of  the  Mississippi,  a  portion  of  which  is  exhibited  in  the  map  and 
section  (Figs.  21,  22),  illustrates  the  erosive  power  of  great  rivers.  At  Vicksburg 
the  alluvial  bottom  is  about  65  miles  wide,  and  the  eastern  bluff'  200  feet  high,  the 
western  being  a  little  lower  and  less  precipitous.  The  strata  in  the  opposite  bluffs 
correspond  throughout,  in  such  manner  as  to  prove  their  former  continuity,  show- 
ing conclusively  that  the  valley,  vast  as  it  is,  is  the  result  of  erosion. 

3.  The  sinuosity  of  the  course 


through  the  bottom-land  is  some- 
times so  great  that  the  length  of 
the  stream,  between  two  given 
points,  is  twice  or  thrice  the  dis- 
tance in  a  direct  line. 

The  slope  of  the  bottom  is 
usually  so  slight  that  a  trifling 
obstacle  may  deflect  the  stream 
from  its  direct  course,  turning  it 
towards  one  or  the  other  bank. 
When  this  is  the  case,  the  in- 
creased erosion  of  the  bank 
against  which  it  is  thrown,  grad- 
ually exhausts  the  force  of  the 
stream ;  the  current  slackens, 
and  the  debris,  no  longer  carried 
forward,  accumulate  in  the  bed, 
forming  an  obstacle  to  the  con- 
tinuance of  the  stream  in  the 
new  course.  Thus  it  is  again 
deflected,  to  repeat  the  process 
on  the  opposite  bank,  forming  a  series  of  curves  of  various  sizes. 

Streams  of  great  volume  and  power  yield  less  readily  to  obstacles, 
and  are  less  easily  deflected  from  a  course  once  established,  than 
small  streams  ;  hence  their  windings  are  much  larger. 

The  inequality  of  the  bends  in  the  Mississippi  and  the  Bayou  Macon,  on  the 
same  slope  and  in  the  same  alluvial  bottom,  shown  in  Fig.  21,  affords  a  striking 
illustration  of  this  fact. 

The  peninsulas  inclosed  by  the  windings  of  a  river  (as  at  a,  in  figure  21),  are 
eroded  on  both  sides  by  the  current,  more  especially  at  n;  and  the  isthmus  is 
sometimes  entirely  cut  through,  forming  an  island.  If  the  main  volume  of  the 
stream  takes  the.direct  course,  across  n,  the  accumulation  of  debris  along  its  mar- 
gin may  finally  dam  the  old  channel,  producing  a  lake,  as  at  c. 

4.  In  high  water,  the  power  of  the  river  being  greatly  in- 
creased, the  current  has  a  tendency  to  take  a  more  direct  course. 
Fresh  channels  may  thus  be  eroded,  and  the  windings  changed,  so 
that  when  the  flood  subsides  the  main  stream  has  a  new  position. 
In  this  case  the  old  channel  is  occupied  by  a  minor  stream,  called  a 
bayou,  or  by  one  or  more  lakes ;  or,  having  been  filled  with  alluvial 
materials,  it  is  entirely  abandoned. 


FIG.  23.      THE  DELTA    OP   THE   NILE. 


The  nature  of  the  soil,  made  up  as  it  is  by  successive  layers  of 
loose  materials,  facilitates  these  changes  ;  and  the  bottom-land  fre- 
quently presents,  through  its  entire  breadth,  a  network  of  bayous, 
intermingled  with  lakes,  all  more  or  less  connected  with  the  main 
stream. 


III.  Transportation. 

1.  The  AMOUNT  of  transportation  going  on  in  the  rivers  of  the  con- 
tinents is  beyond  calculation.  It  is  estimated  that  the  sediment  an- 
nually borne  by  the  Mississippi  into  the  Gulf  of  Mexico  is  sufficient 
to  cover  one  square  mile  to  the  depth  of  268  feet;  while  the  annual 
deposit  of  the  Ganges,  in  the  Bay  of  Bengal,  would  cover  an  equal 
area  to  the  depth  of  228  feet.  These  are  but  examples  of  the  work 
done  by  the  great  streams  in  all  parts  of  the  Earth. 

2.  Mode.  Streams,  throughout  their  course,  hold  in  suspension 
more  or  less  of  fine  earthy  matter,  forming  mud  or  silt ;  and  great 
quantities  of  heavier  materials  —  like  sand,  gravel,  and  pebbles  — 
are  pushed  along  the  channel  by  the  current. 

In  the  upper  course,  boulders 
and  large  pebbles  cover  the  bed 
of  the  stream,  but  the  heavier  of 
these  are  gradually  left  behind, 
or  carried  onward  only  in  fresh- 
ets. The  lighter,  borne  onward 
by  the  current,  are  reduced  by 
friction  to  gravel  and  coarse 
sand,  which  form  the  bed  in  the 
middle  course ;  and  these,  in  turn, 
are  successively  ground  up,  or 
left,  only  fine  sand  or  silt  being 
transported  to  the  mouth. 

These  earthy  substances  are 
derived  from  every  part  of  the 
river  basin,  through  the  agency 
of  rains,  frosts,  slow  chemical 
decomposition,  and  the  erosion  of 
the  streams  themselves.  They 
are  always  mingled  with  more  or 
less  of  vegetable  and  animal 
matter,  which  has  fallen  or  been 

washed  into  the  river,  and  forms  a  valuable  addition  to  the  soil  of 

the  bottom-lands. 


IV.  Deposit. 

1.  The  Deposit  of  the  materials  transported  by  rivers,  is  greater 
on  the  immediate  banks,  and  at  the  bottom  of  the  stream,  than  on 
the  more  remote  inundated  surface,  to  which  only  the  finest  mud  is 
borne ;  and  it  increases  with  the  slackening  of  the  current  as  the 
river  nears  the  sea.  The  larger  portion,  however,  is  borne  onward  to 
the  mouth,  and  deposited  in  the  waters  into  which  the  river  discharges. 

The  combined  forces  of  the  waves  and  the  river  currents,  acting 
in  opposite  directions,  frequently  heap  up  the  sediment  so  as  to  form 
a  sand-bar  across  the  river  mouth,  at  a  greater  or  less  distance  from 
the  shore.  The  formation  of  such  a  bar  favors  the  deposit  of  sedi- 
ment behind  it,  and  hastens  that  encroachment  of  the  land  upon  the 
sea,  to  which  the  rivers  are  constantly  contributing.  Most  of  the 
rivers  of  our  Southern  States  afford  examples  of  this  formation. 


50 


RIVERS. 


2.  Deltas.  If  there  be  nothing  to  displace  the  alluvial  material 
deposited  around  the  mouth  of  a  great  stream,  it  accumulates  from 
year  to  year,  and  finally  reaches  the  surface,  forming  a  flat,  moist 
plain.  Through  this  the  stream  advances,  usually  by  several  dis- 
tinct channels,  in  sluggish  currents,  to  the  waters  beyond.  Thus 
great  rivers  gradually  pave  their  way  into  the  sea,  building  up  a 
constantly  enlarging  area  of  alluvial  land,  called  a  delta,  from  its  re- 
semblance in  form  to  the  Greek  letter  delta  (A).     See  Fig.  23. 

Deltas,  therefore,  are  but  expansions  and  prolongations  of  the 
alluvial  river  bottom.  They  are  gradually  elevated  by  deposits  dur- 
ing inundation,  but  never  rise  much  above  the  sea  level,  their  limit 
being  the  level  of  the  stream  at  high  water.  Only  two  thirds  of  the 
great  delta  of  the  Mississippi,  the  area  of  which  is  estimated  at 
12,300  square  miles,  is  above  the  level  of  the  Gulf,  one  third  being 
a  sea  marsh. 

The  accumulation  of  alluvial  deposits  on  the  immediate  banks  of 
the  stream,  usually  raises  them  above  the  general  level  of  the  delta, 
while  the  level  of  the  stream  is  raised  correspondingly  by  deposits 
in  the  bed.  Thus  it  happens  that,  though  the  channel  extends  deep 
below  the  level  of  the  sea,  the  surface  of  the  stream  flows  along  the 
summit  of  a  swell,  from  which  the  land  descends  on  each  side. 


%h.y&.^c- 


a,  6.  Levees  upon  the  banks,     c.  Channel,     rf,  e.  Marshes  often  inundated. 
FIG.  24.      SECTION  OF  THE   MISSISSIPPI   WITHIN   THE    DELTA. 

In  the  Mississippi  delta,  for  example,  the  slope  of  the  ground  from  the  margin 
of  the  stream,  exhibited  in  Fig.  24,  is  about  seven  feet  for  the  first  mile  ;  while 
the  descent  of  the  stream,  in  the  direction  of  its  course,  averages  less  than  two 
inches  to  a  mile  throughout  the  delta. 

The  slope  of  the  surface  of  deltas  from  the  stream,  being,  in  general, 
greater  than  the  slope  of  the  stream  in  the  direction  of  its  course, 
the  overflowing  waters  tend  to  descend  the  former  rather  than  keep 
the  direction  of  the  channel.  Again,  the  facility  with  which  the 
soil  of  the  delta  can  be  eroded,  promotes  the  formation  of  new  chan- 
nels during  inundation. 

These  two  facts  combined  explain  the  tendency  of  all  great  rivers 
to  divide  into  several  branches,  before  losing  themselves  in  the  sea  ; 
and  account  for  the  large  number  of  divergent  streams  which  thread 
every  delta,  each  contributing  a  share  to  its  enlargement. 

The  Mississippi  delta,  one  of  the  most  extensive,  affords  a  striking  illustration 
of  this  tendency  to  division.  Numerous  branches  diverge  from  the  river  through- 
out the  vast  delta  :  and  the  main  stream,  flowing  upon  a  long,  narrow  tongue  of 
sand,  again  divides,  near  its  termination,  into  four  principal  channels. 

V.  Rapids  and  Cataracts. 

The  variations  in  the  slope  of  a  river  bed,  arising  from  unequal 
erosion,  or  from  the  original  irregularities  in  the  surface,  give  rise  to 
rapids  and  falls. 

The  first  occur  where  an  increased  slope  causes  the  stream  to  flow 
with  more  than  its  average  velocity.  The  second  are  caused  by 
nearly  perpendicular  rocky  walls,  down  which  the  foaming  water 
descends  in  picturesque  cascades,  or  imposing  cataracts.  Usage, 
however,  often  confounds  these  names. 

The  famous  "  Cataracts  of  the  Nile  "  are  merely  rapids  which  im- 
pede, but  do  not  entirely  obstruct,  the  navigation  as  cataracts  must. 
The  so  called  Falls  of  St.  Anthony,  in  the  upper  Mississippi,  and  the 
rapids  of  the  St.  Lawrence,  above  Montreal,  are  among  tbe  finest 
rapids  in  American  rivers. 


The  highest  falls  are  in  the  upper  course  of  rivers,  in  mountainous 
regions  ;  the  greatest  and  most  imposing,  in  their  middle  course. 
Among  the  former  the  Yosemite  Fall,  in  California,  is  probably 
the  most  remarkable.  It  descends  an  almost  perpendicular  ledge  of 
rocks  more  than  2,500  feet  high,  to  the  bottom  of  the  Yosemite 
valley,  forming  three  separate  cataracts.  The  first  falls  1,500  feet  to 
a  shelf  of  rock ;  the  second  descends  from  this  shelf  in  a  series  of  cas- 
cades through  626  feet ;  and  the  third  makes  the  final  plunge  of  400 
feet,  to  the  foot  of  the  precipice. 

The  Keelfoss,  in  Norway,  the  highest  fall  in  Europe,  has  an  unin- 
terrupted descent  of  2,000  feet ;  and  the  Cascade  of  Gavarnie,  in  the 
Pyrenees,  falls  from  a  height  of  more  than  1,300  feet.  The  Staub- 
bach,  in  the  Swiss  Alps,  descends  a  precipice  of  900  feet,  and  is  re- 
duced to  spray  before  reaching  the  bottom. 

The  Fall  of  Tequendama,  in  the  river  Bogota,  among  the  Andes, 
precipitates  itself  560  feet  into  a  deep  recess,  amidst  the  most  gor- 
geous tropical  vegetation. 

Among  the  great  cataracts,  in  the  middle  course  of  rivers,  that  of 
Niagara  takes  the  first  rank  by  reason  of  the  volume  of  water  falling. 
The  river,  which  is  the  sole  outlet  of  the  great  lakes,  and  is  more 
than  half  a  mile  wide,  pours  itself,  in  two  vast  sheets,  over  a  preci- 
pice 160  feet  high. 

The  Shoshonee  Falls,  in  Snake  River,  in  Idaho;  the  Victoria  Falls, 
in  the  Zambesi ;  the  Falls  of  the  Cavery,  in  India,  one  of  which  is  500 
feet  in  height ;  and  the  Falls  of  the  Rhine  —  but  60  feet  high  —  are 
said  to  equal  Niagara  in  picturesque  beauty,  though  all  are  far  sur- 
passed by  it  in  grandeur. 


ANALYSIS   OF   SECTION  I. 

I.  Sources  and  Systems  of  Kivers. 

1   Sources. 

a.  Definition  of  springs. 

b.  Quantity  of  water.    Most  copious  where. 

c.  Flow  how  differing. 

d.  Explanation  of  intermittent  springs. 

e.  Situation  of  most  springs. 

f.  Temperature. 

2.  Formation  of  River  Systems. 

a.  Direction  of  flow. 

b.  Position  of  main  stream  of  system. 

c.  Example  in  Mississippi  system. 

d.  River  basin. 

e.  Water-shed. 

3.  Amount  op  Water. 

a.  Depends  on  what 

b.  Influence  of  forests. 

4.  Agency  of  Rivers. 

II.  Erosion. 

1.  In  Upper  Course. 

a.  Where  taking  place. 

b.  Extent  of. 

c.  Effect  of  unequal  hardness  of  rocks. 

2.  In  Middle  Course. 

a.  Where  taking  place.     Where  greatest      Debris. 

b.  Result  of  lateral  erosion.     Soil  of  bottom-laud. 

c.  Example  in  Mississippi  Valley. 

Width  of  botlom. 
Height  of  bluffs 
Evidence  of  origin  by  erosion. 
3-  Sinuosity  of  Course. 

a.  Amount. 

b.  How  caused. 

c.  Size  of  bends.     Example. 

d.  Erosion  of  peninsulas  within  bends. 
4.  Changes  in  Hioa  Water. 

a.  How  caused. 

b.  Old  channel  how  occupied. 

c.  Influence  of  alluvial  soil  of  bottom. 

III.  Transportation. 

1.  Amount  of.    Examples. 

2.  How  Effected. 

a.  Materials  in  suspension. 


LAKES. 


51 


b.  Materials  pushed  along. 

In  upper  course. 

In  middle  and  lower  course. 

c.  Earthy  materials  whence  derived. 

d.  Intermingling  of  other  matter. 
IY.  Deposit. 

1.  How  Varying.    Formation  of  Sand  Bars. 

2.  Deltas. 

a.  Result  of  deposit  in  sea. 

b.  Delta.     Real  character. 

Elevation. 

Variation  of  level.     Example. 
Effect  of  slope  of  delta  from  stream. 
Tendency  of  great  streams  to  divide  near  s 
Example  in  Mississippi. 
V.  Rapids  and  Cataracts. 

a.  How  caused. 

b.  Examples  of  rapids. 

c.  Examples  of  high  falls. 

d.  Examples  of  great  cataracts. 


II. 


LAKES. 


I.  Mountain  Lakes. 


Lakes,  being  but  accumulations  of  water  in  the  natural  depres- 
sions in  the  surface  of  the  continents,  derive  their  form  and  charac- 
ter from  the  nature  of  their  basins,  and  of  the  regions  in  which 
they  are  found. 

Mountain  lakes, 
which  are  valleys 
or  chasms  filled  by 
streams,  are  long 
and  narrow,  rarely 
of  extensive  area, 
but  often  of  great 
depth.  Examples 
of  this  class  are 
found  in  Lakes 
Champlain  and 
George,  among 
the  Appalachian 
Mountains ;  Lakes 
Constance  and  Ge- 
neva, on  the  north- 
ern  side  o f  t h e 
Alps ;  and  Lake' 
M  aggiore  and 
Lake  Como,  on  the 
south  side  :  all  of 
which  are  re- 
nowned for  the 
loveliness  of  their 
shores,  or  the  grandeur  of  the  surrounding  mountain  scenery. 

Lake  Maggiore,  which  is  hardly  three  miles  wide,  is,  according  to  the 
Italian  engineers,  2,623  feet  deep  —  more  than  double  the  depth  of 
Lake  Superior  —  its  basin  reaching  1,936  feet  below  the  sea  level. 

The  forms  of  mountain  lakes  are  very  irregular,  for  the  water 
often  covers  several  contiguous  and  connected  valleys.  This  is  the 
case  in  Lake  Como,  which  has  two  long  arms ;  and  Lakes  Lucerne 
and  Lugano,  each  of  which  fills  four  distinct  valleys,  meeting  one 
another  nearly  at  right  angles. 

II.  Lakes  in  Plains. 

The  lake  basins  in  plains  and  plateaus  are,  usually,  simple  de- 
pressions in  a  comparatively  uniform  surface.  The  lakes  are,  there- 
fore, often  of  great  size,  broad  in  proportion  to  their  length,  but  of 
little  depth  compared  with  their  area. 

The  largest  lakes  of  the  globe  —  the  Caspian  and  Aral  Seas,  and 
the  great  North  American  and  African  lakes  —  and  the  largest  in 


A    PART  OF   LAKE   MAQGIORF.    NEAR    LorARNO. 


Europe  and  South  America,  all  belong  to  this  class.  Their  vast  ex- 
panse, together  with  the  tameness  of  their  shores,  deprives  them  of 
the  picturesque  beauty  which  characterizes  mountain  lakes. 

Most  lakes  receive  and  send  forth  streams,  of  which  they  seem 
properly  to  be  but  expansions.  They  form  reservoirs,  which,  receiv- 
ing the  surplus  waters  in  time  of  freshets,  equalize  the  flow  of  rivers, 
and  prevent  destructive  inundations.  In  their  basins,  the  wild  moun- 
tain torrents  find  rest,  and  the  muddy  waters  deposit  their  sediment, 
and  flow  out  pure  and  transparent,  with  a  gentle  current. 

III.  Salt  Lakes. 

1.  Chaeactekistics.  Numerous  lakes  in  the  interior  of  the  con- 
tinents, though  receiving  affluents,  have  no  outlet.  Their  waters 
are  chiefly  lost  by  evaporation,  though  some  portion  may  be  absorbed 
by  the  sandy  soil.     Lakes  of  this  class  are  usually  salt. 

2.  Cause  of  Saltness.  The  surfaces  of  the  continents  having 
been  the  beds  of  the  primeval  oceans,  the  presence  of  salt  in  the 

soil  is  a  natural 
consequence. 
Fresh  water 
streams  and  lakes 
were  formed  only 
after  the  soil  had 
been  thoroughly 
washed  by  rains, 
and  the  salt  car- 
ried away  by 
streams  into  the 
ocean. 

If  the  streams 
receiving  the  sub- 
stances  washed 
from  the  soil  by 
the  rainfall,  do  not 
flow  away  to  the 
ocean,  but  enter 
inland  basins 
without  outlet,  the 
lakes  formed  in 
those  basins  will 
necessarily  be 


salt.  Their  size 
will  depend  upon  the  relation  between  the  amount  of  rain  and  the 
rapidity  of  evaporation  in  the  region  whose  surplus  waters  they 
receive. 

3.  Examples.  The  Great  Salt  Lake  of  Utah,  in  the  Great 
American  Basin,  is  one  of  the  finest  examples  of  its  class.  The 
Caspian  and  Aral  Seas,  at  the  bottom  of  the  vast  depression  be- 
tween Europe  and  Asia,  are  the  most  extensive  salt  lakes.  The 
former  has  about  four  times  the  area  of  Lake  Superior ;  and  the 
latter  is  a  little  larger  than  Lake  Michigan. 

The  Caspian,  though  receiving  the  Volga,  the  largest  river  of 
Europe,  evaporates  so  much  water  that  its  surface  is  about  83  feet 
lower  than  that  of  the  Mediterranean,  varying  with  the  seasons. 
Many  lakes  in  its  neighborhood  disappear  entirely  in  the  heat  and 
drought  of  summer,  leaving  their  beds  covered  with  a  crust  of  pure 
white  crystalline  salt.  From  one  of  these  —  Lake  Elton,  between 
the  Ural  and  the  Volga  — 100,000  tons  of  salt  are  taken  annually. 

The  Dead  Sea,  in  Syria,  east  of  the  southern  angle  of  the  Medi' 
terranean,  is  a  remarkable  lake  in  which  the  salt  has  accumulated 


52 


DRAINAGE   OF  NORTH   AMERICA. 


until  the  water  is  converted  into  a  heavy  brine.  It  may  be  the  rem- 
nant of  an  ancient  sea  of  much  greater  extent,  which  has  been  grad- 
ually reduced  in  size  by  the  excess  of  evaporation  over  the  supply  of 
water  in  its  basin. 

This  celebrated  body  of  water  lies  in  the  deepest  part  of  a  long 
chasm  or  valley,  which  is  sunk  not  less  than  4,000  feet  below  the 
level  of  the  surrounding  country.  The  surface  of  the  lake  is  1,286 
feet,  and  its  bottom  2,500  feet,  below  the  level  of  the  Mediterranean. 

Its  feeder,  the  river  Jordan,  accomplishes  nearly  its  entire  course 
below  the  level  of  the  sea,  the  only  known  instance  of  the  kind. 
The  beautiful  lake  of  Tiberias,  the  scene  of  so  many  of  the  miracles 
of  Jesus,  which  is  but  an  expansion  of  the  Jordan  in  its  upper  course, 
is  about  650  feet  below  the  surface  of  the  Mediterranean. 

IV.  Geographical  Distribution  of  Lakes. 

1.  Lakes  abe  most  numerous  in  the  central  and  northern  por- 
tions of  Asia,  Europe,  and  North  America.  The  southern  conti- 
nents, except  Africa,  have  comparatively  few. 

2.  Asia  is  preeminently  the  continent  of  salt  lakes.  They  occur 
in  countless  numbers,  both  in  the  steppes  north  of  the  Caspian  and 
Aral,  and  in  all  the  interior  plateaus.  Lakes  of  fresh  water  are 
also  found  among  the  Altai  Mountains  and  adjacent  chains.  Lake 
Baikal,  one  of  these,  is  the  largest  mountain  lake  known,  being 
nearly  500  miles  long. 

3.  In  Europe,  the  most  characteristic  and  celebrated  lakes  are 
those  which  adorn  the  Alps  of  Switzerland  and  Scandinavia,  and 
the  less  lofty  mountain  chains  of  the  British  Isles.  But  the  lar- 
gest lakes  are  found  in  the  low  lands  and  slight  swells  which  sur- 
round the  Baltic  Sea,  in  western  Russia  and  Sweden.  Lakes  Ladoga 
and  Onega,  in  Russia,  and  Wener  and  Wetter,  in  Sweden,  are  the 
largest  in  Europe. 

4.  North  America  is  peculiarly  rich  in  great  lakes.  No  conti- 
nent presents  a  more  remarkable  series  than  that  which  stretches 
from  northwest  to  southeast,  through  the  central  plains,  along  the 
line  of  contact  of  the  oldest  geological  formations  of  the  continent. 
This  series  includes  Great  Bear  and  Great  Slave  Lakes,  Athabasca 
and  Winnipeg,  and  the  five  great  lakes  of  the  St.  Lawrence,  with 
many  of  less  area. 

Innumerable  small  lakes  are  scattered  throughout  the  middle  por- 
tions of  the  central  plain,  and  the  northern  and  less  regular  part  of 
the  Appalachian  mountain  region ;  but  south  of  the  parallel  of  Lake 
Erie  there  is  an  almost  entire  absence  of  lakes,  whether  large  or 
small. 

5.  In  Africa  the  great  plateau  lakes  are  typical  of  the  continent. 
The  Victoria  Nyanza  and  Albert  Nyanza,  feeding  the  White  Nile  ; 
Tanganyika,  whose  outlet  is  unknown ;  Tzana,  at  the  head  of  the 
Blue  Nile  ;  and  Lake  Nyassi,  in  the  Zambesi  basin,  all  rest  on  the 
high  plateaus  of  Central  Africa.  Lake  Tchad  alone,  among  large 
African  lakes,  is  surrounded  by  low  plains. 


analysis  of  section  n. 


I.  Mountain  Lakes. 


II.  Lakes  In  Plains. 


a.  Form  and  character  of  lakes  due  to  what. 

b.  Characteristics  of  mountain  lakes. 

c.  Examples. 

d.  Peculiarities  of  form.   * 

a.  Basins  and  characteristics. 

b.  Great  lakes  of  globe. 

c.  Connection  of  streams  with  lakes. 

d.  Effects  produced  by  lakes. 


III.  Salt  Lakes. 

1.  Characteristics. 

2.  Cause  op  Saltness. 

a.  Salt  in  soil. 

b.  Formation  of  fresh  water  streams  and  lakes. 

c.  Lakes  in  inclosed  basins. 
8.  Examples. 

a.  Great  Salt  Lake. 

b.  Caspian  and  Aral. 

c.  Dead  Sea. 

Its  character. 
Its  basin. 
Its  feeder. 
IV.  Distribution  of  Lakes. 

a.  Where  most  numerous. 

b.  Lakes  of  Asia. 

c.  Lakes  of  Europe. 

d.  Lakes  of  North  America. 

e.  Lakes  of  Africa. 


III.  — DRAINAGE   OF  NORTH  AMERICA. 

I.  Influence  of  the  Continental  Structure. 

The  position  of  the  main  axis  of  the  continent,  nearer  the  Pa- 
cific ocean  than  the  Atlantic,  causes  all  the  longest  streams  to  enter 
the  Atlantic  and  Arctic  basins,  while  those  of  secondary  rank  enter 
the  Pacific.  Again,  the  position  of  the  two  fundamental  highlands 
near  opposite  shores,  throws  the  larger  part  of  the  flowing  waters  into 
the  central  depression,  where,  under  the  influence  of  converging 
slopes,  they  are  combined  into  a  few  great  systems. 

Third,  the  presence  of  a  secondary  water-shed,  the  Height  of 
Land,  crossing  the  central  plains,  divides  these  systems  into  two 
groups :  on  the  south  the  Mississippi  and  St.  Lawrence  systems  ; 
on  the  north  the  Mackenzie  and  Saskatchewan  systems. 

Fourth,  a  series  of  great  depressed  basins,  forming  three  natural 
groups,  give  rise  to  the  most  remarkable  belt  of  lakes  on  the  face . 
of   the   globe,  belonging  to  three   river  systems  —  the  Mackenzie,  . 
the  Saskatchewan,  and  the  St.  Lawrence. 

II.  The  Main  Water-shed. 

The  Rocky  Mountains,  which,  with   their  southward  extension, ' 
constitute  the  main  axis  of  the  continent,  form  through  their  entire 
extent,  the  water-shed  between  the  streams  of  the  Pacific  slope  and 
those  of  the  central"  plains. 

But  the  middle  portion,  in  which  the  altitude  of  passes  ranges 
from  7,500  to  11,000  feet,  and  that  of  peaks  from  12,000  to  15,000, 
forms  the  most  remarkable  hydrographical  centre. 

From  Union  Peak,  in  Wind  River  Mountains,  water  descends 
on  three  sides,  to  the  Mississippi,  the  Columbia,  and  the  Colorado 
river  ;  and  within  a  distance  of  600  miles  south  of  this  peak,  six  of 
the  greatest  rivers  of  the  continent  have  their  origin.  Eastward 
flow  the  Missouri,  the  Platte,  and  the  Arkansas  ;  Avestward  the 
head  waters  of  the  Columbia,  and  Colorado ;  and  southward  the 
Rio  Grande  del  Norte. 

Farther  north,  in  British  America,  is  a  similar  centre  from  which 
flow  four  streams  :  on  the  east  the  Saskatchewan  and  the  Macken- 
zie ;  on  the  west  the  Yukon  and  the  Frazer. 


III.  The  Mississippi  System. 

1.  The  Basin  of  the  Mississippi  consists  of  the  three  long  slopes 
which  form  the  southern  half  of  the  great  central  depression  of  the 
continent  —  the  slope  from  the  Rocky  Mountains  eastward ;  from 
the  Appalachian  Mountains  westward  ;  and  from  the  Height  of 
Land  southward. 


DRAINAGE  OF  NORTH  AMERICA. 


53 


2.  Three  GEEAT  tributaries,  each  representing  one  of  these 
slopes,  form,  by  their  union,  the  main  stream,  namely :  the  Missouri, 
much  the  longest,  from  the  west ;  the  Ohio,  contributing  the  greatest 
amount  of  water,  from  the  east ;  and  the  upper  Mississippi,  from 
the  north. 

The  channel  of  each  of  these  great  affluents  is  fixed  by  the  con- 
figuration of  the  surface.  The  Mississippi  flows  along  the  line 
in  which  the  inner  slopes,  from  the  primary  and  the  secondary  high- 
lands of  the  continent,  meet ;  the  Missouri  and  Ohio  lie  where  these 
slopes  are  met  by  the  subordinate  one  from  the  height  of  land.  The 
first,  though  so  much  shorter  than  the  Missouri  before  their  con- 
fluence, properly  gives  its  name  to  the  system,  since  it  occupies  the 
main  or  central  valley. 

Two  other  tributaries  of  great  length,  the  Arkansas  and  Red 
rivers,  together  with  many  miner  ones,  swell  the  waters  of  the  main 
stream,  and  establish  means  of  intercommunication  between  all  parts 
of  this  vast  basin. 

The  western  af- 
fluents have  the 
most  extensive  ba- 
sins and  the  long- 
est courses,  but 
they  transport 
comparatively  lit- 
tle water ;  white 
the  eastern  con- 
tribute  a  large 
amount  of  water 
from  limited  areas. 

The  Ohio,  whose 
entire  basin  lies  in 
the  path  of  the 
moist  southwest- 
erly winds  from 
the  Gulf  of  Mex- 
ico, is  the  largest 
contributor. 

The  following  ta- 
ble gives  the  area 
of  drainage,  length  of 

course,  and  average  discharge  of  water  per  second,  of  each  of  the  main  tributaries 
of  the  Mississippi,  and  of  the  entire  system.  The  figures  are  from  the  "  Report 
upon' the  Physics  and  Hydraulics  of  the  Mississippi  River,  by  the  U.  S.  Topograph- 
ical Engineers." 


TABLE    OF    STREAMS    OF    THE    MISSISSIPPI    SYSTEM. 


VIEW   ON    LAKE    SUPERIOR.      llIE   PICTURED    ROCKS. 


Kivers. 


Missouri 

Ohio 

Upper  Mississippi    .    . 

Arkansas 

Red 

The  Smaller  Tributaries 
Mississippi  entire     .     . 


Area  of  Basin 


518,000  Eng.  sq. 

21 1,000  " 

169,000  " 

18(1,000  " 

07,000  " 

57,000  " 

1,244,000  " 


miles. 


Length  in  English  miles. 


2,908 
1,265 
1,M0 
1,514 
1,200 

4,200  (Lower  Miss.  &  Mo.) 


Mean  Discharge 
per  second. 


120,000  cub.  ft. 

158,000 

105,000  " 

63,000  " 

57,000  " 

172,000  " 

675,000  " 


The  real  sources  of  this  noble  river  are,  however,  that  chain  of 
magnificent  lakes,  of  which  it  is  the  only  outlet. 

The  extent  of  its  basin  —  only  about  two-fifths  of  that  of  the 
Mississippi  —  is  singularly  small  compared  with  the  magnitude  of 
the  stream,  and  with  the  volume  of  water  it  discharges  into  the  sea, 
which  is  said  to  be  more  than  double  that  of  the  Mississippi. 


V.  Other  Systems. 

The  Yukon,  draining  the  northern  extremity  of  the  Pacific 
highlands,  the  Rio  Grande  del  Norte,  draining  the  southern  part 
of  the  Rocky  Mountains,  and  the  Columbia  and  Colorado,  draining 
the  central  portions  of  the  Pacific  slope,  complete  the  list  of  great 
rivers  in  North  America.  None  of  these  is  less  than  1,000  miles  in 
length,  while  the  longest,  the  Yukon,  is  1,600  miles  long. 

The  minor 
streams  form  five 
groups.  The  first 
group  drain  the 
short  slopes  sur- 
rounding Hudson 
Bay  ;  the  second, 
the  Atlantic  slope 
of  the  Appala- 
chian mountains ; 
the  third,  the  short 
slopes  around  the 
Gulf  of  Mexico. 

The  fourth 
group  drain  the 
Pacific  slopes  of 
the  Sierra  Nevada 
and  Cascade 
Mountains.  The 
fifth  lie  in  the  in- 
closed basin,  b  e  - 
tween  the  Sierra 
Nevada  and  the 
Rocky  Mountains, 
and  discharge  into  salt  lakes,  among  which  the  Great  Salt  Lake  of 
Utah  is  the  largest. 

TABLE   OF   NORTH   AMERICAN   RIVERS    AND   LAKES. 


Rivers. 


IV.  St.  Lawrence  System. 

The  St.  Lawrence,  like  the  upper  Mississippi,  rises  in  the  height 
of  land  in  the  very  heart  of  the  continent,  its  remote  source,  the 
St.  Louis  River,  being  only   an  inconsiderable   stream. 


Mississippi  (Lower  &  Mo.) 

Mackenzie 

St.  Lawrence    .... 
Saskatchewan   .... 

Columbia 

Colorado 

Rio  Grande  del  Norte     . 
Yukon         .    .    ;    .    . 


Area  of  Ba- 

Length of 

sin  in  Eng. 

Course  in 

Sq.  miles. 

Eng.  miles. 

1.244,000 

4,200 

590,000 

2,300 

480,000 

2,000 

478,000 

1,900 

298,000 

1,020 

257,000 

1,000 

240,000 

1,500 

200,000 

1,600 

Colorado,  Texas 
Brazos  .  .  .  . 
Alabama  .  .  . 
St.  John  .  .  . 
Susquehannah  . 
Hudson  .  .  . 
Connecticut  .  . 
Savannah       .    . 


Area  of  Ba- 
sin in  Eng. 
sq.  miles. 


38,000 
34,000 
33,000 
26,500 
25,000 
12,000 
10,600 
10,000 


Length  of 

Course  in 

Eng.  miles. 


600 
650 
650 
450 
400 
330 
360 
800 


Lakes. 


Superior 
Michigan 
Huron 
Erie    .     . 


Great  Bear  Lake 
Winnipeg    .    . 


Area  in 

Altitude 

Depth  in 

Bq.  miles. 

in  feet. 

feet. 

31,400 

600 

1.200 

25,600 

674 

1,000 

23,800 

674 

1,000 

10.000 

665 

80 

9,300 

230 

- 

8,900 

628 

- 

Lakes. 


Great  Slave  Lake 
Onts-'D  .  .  . 
Nicaragua  .  . 
Great  Salt  Lake 
Athabasca  .  . 
Lake  of  the  Woods 


Area  in 
sq.  miles. 


Altitude 
in  feet. 


8,300 
7,300 
3,600 
3,200 
3,200 
500 


235 

4,200 
600 
977 


Depth  in 
feet. 


600 


54 


DRAINAGE   OF  SOUTH   AMERICA. 


This  table  shows  that  the  four  great  river  systems  of  the  conti- 
nent belong  to  the  central  plains ;  and  those  of  the  second  order  to 
the  Pacific.  The  coast  rivers,  as  compared  with  these,  are  inconsid- 
erable ;  and  the  Gulf  rivers,  both  in  area  of  basin  and  length  of 
course,  exceed  those  flowing  directly  into  the  Atlantic.  The  great 
lakes  are  all  within  the  central  plains,  belonging  to  the  St.  Law- 
rence, the  Mackenzie,  and  the  Saskatchewan  system. 


ANALYSIS  OF  SECTION   III. 

I.  Iit^Inence  of  Continental  Structure. 

a.  Of  position  of  main  axis. 

b.  Of  positions  of  fundamental  highlands. 

c.  Of  secondary  water-shed. 

d.  Of  depressed  basins. 

II.  Alain  Water-shed  of  North  America. 

a.  What  constitutes  it. 

b.  Primary  hydrographical  centre. 

c.  Secondary  hydrographical  centre. 

III.  Mississippi  System. 

1.  Basin.    How  Constituted. 

2.  Three  Great  Tributaries. 

a.  Directions. 

b.  Position  of  channels. 

c.  Other  tributaries. 

3.  Amount  of  Water  Transported. 

a.  Western  affluents. 

b.  Eastern  affluents. 

c.  Table  of  Mississippi  system. 

IV.  St.  Lawrence  System. 

a.  Remote  source. 

b.  Real  Source. 

c.  Extent  of  basin. 


V.  Other  Systems* 


a.  Remaining  great  rivers. 

b.  Minor  streams. 


VI.  Table  of  North  American  Rivers. 

a.  Relative  rank  of  systems. 

b.  Position  of  lakes. 


IV.— DRAINAGE   OF  SOUTH   AMERICA. 

I.  Influence  of  the  Continental  Structure. 

The  position  of  the  two  axes  of  the  continent,  near  opposite 
shores,  gives  to  South  America  the  same  general  plan  of  drainage  as 
exists  in  North  America  ;  but  the  greater  unity  of  structure  in  the 
former,  gives  rise  to  a  still  more  extensive  combination  of  streams 
than  in  the  latter. 

Thus  it  is  that  South  America,  though  ranking  fourth  among  the 
continents  in  size,  possesses  the  most  extensive  river  system  of  the 
globe,  the  Amazon,  whose  area  of  drainage  is  2,300,000  square 
miles,  more  than  double  that  of  any  other  system. 

The  effect  of  the  extreme  inequality  of  the  continental  slopes,  is 
seen  in  the  fact  that  only  mountain  torrents  enter  the  Pacific ; 
while  three  vast  systems,  including  very  nearly  all  the  considerable 
streams  of  the  continent,  enter  the  Atlantic. 

Each  of  the  systems  is  especially  connected  with  one  of  the  great 
features  of  the  continental  structure.  The  Amazon  derives  its  main 
waters  from  the  Andes,  but  receives  tributaries  from  both  of  the 
subordinate  highlands.  The  La  Plata  is  the  system  of  the  Brazil- 
ian table-land  ;  and  the  Orinoco,  of  the  mountain  land  of  Guiana ; 
but  each  receives  subordinate  streams  from  the  Andes. 

The  uniformity  of  surface  in  the  interior  plains,  together  with 
their  alluvial  formation,  in  marked  contrast  to  the  central  plains  of 
North  America,  causes  that  entire  absence  of  great  lakes  which  is 
noticeable  in  South  America. 


II.  The  Amazon  System. 

1.  Basin.  This  basin  is  composed  of  the  great  eastern  slope  of 
the  central  Andes,  and  two  subordinate  regions  —  the  northern  slope 
of  the  plateau  of  Brazil,  and  the  southern  of  the  mountain-land  of 
Guiana.  The  Madeira  on  the  south,  and  the  Rio  Negro  on  the 
north,  mark  the  intersections  of  these  slopes. 

2.  Source  of  Waters.  The  main  stream  and  its  greatest  tribu- 
taries are  from  the  Andes.  They  drain  a  continuous  arc  of  moun- 
tains nearly  2,000  miles  in  length,  including  the  highest  portions  of 
the  system.  Streams  of  great  length  and  volume  also  flow  from  the 
Brazilian  plateau,  but  those  from  the  mountain-land  of  Guiana 
are  comparatively  unimportant. 

The  position  of  the  Amazon  in  the  continent,  and  the  source 
whence  its  waters  are  derived,  correspond  to  those  of  the  Saskatch- 
ewan, in  North  America ;  but  while  the  former  ranks  first  among 
the  streams  of  the  earth,  the  latter  is  a  river  of  a  secondary  order. 

3.  The  amount  of  water  transported  by  the  Amazon  system, ' 
surpasses  that  of  other  streams  as  greatly  as  does  the  area  of  its 
drainage.  The  vast  basin  lies  wholly  in  the  latitude  of  most  abun- 
dant tropical  rains,  and  no  barrier  intervenes  to  exclude  from  it 
the  wealth  of  moisture  transported  westward  by  the  trade  winds 
from  the  Atlantic. 

The  broad  estuary,  at  the  mouth  of  the  river,  may  justly  be 
compared  to  a  sea  of  fresh  water  ;  and  for  hundreds  of  miles  from 
the  shore,  the  turbid  yellow  stream  flows  on,  distinct  from  the  clearer 
waters  of  the  surrounding  ocean. 


III.  Other  Systems. 

1.  The  Rio  de  la  Plata  basin  is  similar  in  position  and  struc- 
ture to  the  Mississippi  basin,  and  very  nearly  as  extensive.  It  in- 
cludes the  southern  portions  of  the  interior  plain  and  the  Brazilian 
plateau,  together  with  the  eastern  slope  of  the  Andes  of  Bolivia  and 
Chili.     Only  secondary  tributaries,  however,  flow  from  the  latter. 

The  main  stream  of  this  system  is  the  Parana ;  its  principal  tribu- 
taries the  Paraguay  and  Uruguay.  The  name  of  Rio  de  la  Plata  be- 
longs only  to  the  broad  estuary  at  the  mouth  of  the  Parana. 

2.  The  Orinoco  BASIN  corresponds  in  position  and  structure  to 
the  Mackenzie  basin  of  North  America,  though  its  area  is  consider- 
ably less.  It  includes  the  eastern  slope  of  the  northern  Andes,  the 
northern  plains,  and  the  main  mass  of  the  mountain-land  of  Guiana, 
the  principal  stream  coming  from  the  latter,  and  following  its  base. 

The  Orinoco  and  La  Plata  basins,  however,  can  hardly  be  consid- 
ered as  separated  from  that  of  the  Amazon  by  regular  water-sheds. 
The  head  waters  of  the  Paraguay,  in  the  La  Plata  system,  mingle 
with  those  of  the  Madeira,  during  the  rainy  season,  in  inundated 
swamps.  The  Orinoco  in  its  upper  course  divides,  sending  nearly 
one  third  of  its  water  to  the  Amazon  system,  by  the  Casiquiare,  a 
permanent  stream  comparable  in  size  to  the  Rhine. 

3.  Minor  Streams.  The  San  Francisco,  draining  a  longitudi- 
nal valley  at  the  western  foot  of  the  secondary  continental  axis,  cor- 
responds  to  the  St.  Lawrence  in  North  America.  The  Mapdalena, 
between  the  ranges  at  the  northern  extremity  of  the  Andes,  corre- 
sponds to  the  Yukon  ;  and  the  small  Rio  Negro,  draining  the  south- 
ern extremity  of  the  high  Andes,  to  the  Rio  Grande  del  Norte. 

Thus  the  similarity  in  the  general  plan  of  structure  of  North  and 
South  America,  gives  rise  to  a  marked  resemblance  in  the  position 
and  combination  of  their  streams. 


DRAINAGE   OF  ASIA  AND  EUROPE. 


55 


The  only  large  lakes  in  South  America  are  Lake  Maracaybo  (area 
5,300  square  miles,  altitude,  sea  level)  and  Lake  Titicaca  (area 
3,500  square  miles,  altitude  12,850  feet,  depth  700  feet). 

IV.  Table  of  South  American  Rivers. 


Rivers. 


Amazon  .  . 
Ucayali . 
Purus  . 
Madeira 
Tapajoa  . 
Xingu  . 
Tocantius 
Yapura  . 
Rio  Negro 


Area  of  Ba- 

Length of 

sin  in  Eng. 

Course  in 

sq.  miles. 

Eng.  miles 

2,275,000 

1 
3,750 

140,000 

1,400     | 

140,000 

1,500 

345,000 

2,200 

150,000 

1,200 

130,000 

1,500 

270,000 

1,600 

80,000 

1,200 

280,000 

1,600 

Rivers. 


T.a  Plato,  or  Parana 

Paraguay . 

Uruguay  . 

Pilcomayo 

Yormejo    . 
Orinoco  .     .     . 
San  Francisco 
Magdalena 
Rio  Negro  (southern) 


Area  of  Ba- 
sin in  Eng. 
sq.  miles. 


1,242,000 

560,000 

150,000 

75,000 

50,000 

340,000 

250,000 

95,700 

36,000 


Length  of 
Course  in 
Eng.  miles. 


2,300 

1,400 

1,100 

950 

600 

1,550 

1,550 

"50 

700 


ANALYSIS  OF  SF0PION  IV. 

I.  Influence  of  Continental  Structure. 

a.  Position  of  axes. 

b.  Unity  of  structure. 

c.  Inequality  of  continental  slopes. 

d.  Relation  of  systems  to  structural  features. 

e.  Uniformity  of  interior  plains. 

II.  Amazon  System. 

1.  The  Basin. 

a.  How  constituted. 

b.  Intersection  of  slopes,  how  marked. 

2.  Source  of  Water. 

Corresponding  stream  of  North  America. 

3.  Amount  of  Water  Transported. 

III.  Other  Systems. 

1.  La  Plata  Basin. 

a.  Position  and  structure. 

b.  Regions  included. 

c.  Source  of  main  stream. 

2.  Orinoco  Basin. 

a.  Position  and  structure. 

b.  Regions  included. 

c.  Source  of  main  waters. 

d.  The  Orinoco  and  La  Plata  basins  as  related  to  the  Amazon 

basin.    Connections. 

3.  Minor  Streams. 

a.  San  Francisco. 

b.  Magdalena. 

c.  Rio  Negro. 

IV.  Table  of  South  American  Streams. 


V.  — DRAINAGE   OF  ASIA  AND  EUROPE. 


I.  Eastern  Asia. 

1.  Influence  op  the  Continental  Structure.  The  posi- 
tion of  the  two  axes  of  Asia,  near  the  centre  of  the  main  body  of  the 
continent,  together  with  the  plateau  character  of  the  central  depres- 
sion, gives  to  this  continent  a  plan  of  drainage  quite  opposite  to  that 
pervading  the  New  World.  The  waters  of  the  central  depression 
an-  imprisoned  within  it  by  a  girdle  of  snowy  mountain  chains,  and, 
having  no  outlet,  are  carried  away  by  evaporation. 

The  exterior  slopes,  descending  from  the  central  mass  towards  the 
four  cardinal  points,  send  their  waters,  in  many  separate  streams,  to 
the  adjacent  oceans  and  inland  seas.  Those  upon  the  same  slope 
are  approximately  parallel,  rarely  flowing  together.  Hence  this 
vast  continent  does  not  show  such  extensive  combinations  of  rivers 
as  distinguish  the  great  interior  plains  of  the  New  World. 

2.  Principal  Streams.     Three  great  streams  —  the  Obi,  the 


Yenisei,  and  the  Lena  —  flow  northward,  through  the  vast  plains  of 
Siberia,  into  the  Arctic  Ocean.  Three  others — the  Amoor,  the 
Hoang-ho,  and  the  Yang-tse-Kiang  —  descend  the  eastern  slope, 
through  high  mountains,  valleys,  and  alluvial  plains,  to  the  Pacific. 
On  the  southeast  two  —  the  Mekong  and  Irawaddy  — flow,  between 
long  parallel  mountain  chains,  into  the  Gulfs  of  Siam  and  Bengal. 

Three  on  the  south,  the  "  sacred  streams  "  from  the  Himalayas  — 
the  Sampu  or  Brahmapootra,  the  Ganges,  and  the  Indus  —  enter 
the  Indian  Ocean.  Two  on  the  west — the  Amoo  Daria,  and  the 
Sir  Daria  —  entering  the  Aral  Sea,  complete  the  garland  of  great 
rivers  descending  from  the  central  highlands.  In  the  central  de- 
pression, the  Tarim,  after  a  course  of  1,700  miles,  disappears  amid 
the  sands  of  the  desert  of  East  Turkestan,  in  Lake  Lop,  whose  only 
outlet  is  by  evaporation. 


II.  Western  Asia. 

Western  Asia,  with  its  central  table-land  of  Iran,  and  its  penin- 
sular plateau  of  Arabia,  has  but  one  considerable  river  system,  that 
of  the  Euphrates  and  Tigris,  flowing  into  the  Persian  Gulf.  In  the 
central  depression  of  Iran,  from  which  no  water  finds  its  way  to  the 
ocean,  the  Helmund  has  a  course  of  800  miles,  and  loses  itself  in 
Lake  Hamoon,  in  the  swamps  of  Seistan,  as  the  Tarim  does  in  Lake 
Lop. 


III.  Europe. 

1.  Separate  Hydrographical  Centres.  High  Europe,  on 
the  southwest,  a  mountain-land  with  great  peninsulas,  and  low 
Europe,  on  the  northeast,  a  region  of  vast  plains  —  each  has,  like 
Asia,  a  hydrographical  centre  from  which  streams  radiate  in  every 
direction.  The  snow-crowned  Alps  in  the  former,  and  the  low  Val- 
dai Hills  in  the  latter,  form  these  centres. 

2.  High  Europe.  Four  streams  —  the  Rhine,  the  Danube,  the 
Rhone,  and  the  Po  —  drain  the  entire  system  of  the  Alps.  The 
Rhine  alone  takes  its  course  directly  to  the  ocean,  forcing  its  way  to 
the  sea  through  narrow  and  picturesque  defiles,  across  the  secondary 
highlands  which  surround  the  Alps.  The  others  flow  parallel  with 
the  mountain  mass,  collecting  nearly  all  the  Alpine  waters,  and 
finally  entering  inland  seas. 

Numerous  streams  of  lesser  magnitude  flow  from  the  secondary 
highlands  to  the  adjacent  seas,  with  a  general  direction  towards  the 
northwest  imparted  by  the  slope  of  the  continent  in  that  direction. 

In  each  of  the  three  main  divisions  of  High  Europe  (see  page  36, 
Topic  II.)  are  four  principal  streams.  The  western  has  the  Ga- 
ronne and  the  Loire,  from  the  central  plateau  of  France,  and  the 
Pyrenees ;  the  Seine  and  the  Meuse,  from  the  plateau  of  Langres. 
(See  map,  page  37.) 

The  central  division  has  the  Weser  and  the  Elbe,  from  the  in- 
closed basins  ;  the  Oder  and  the  Vistula,  from  the  outer  slope  of  the 
marginal  highlands.  The  eastern  has  the  Theiss  and  the  Aluta, 
from  the  plateau  of  Transylvania,  with  the  Pruth  and  the  Sereth, 
from  the  Carpathian  Mountains,  all  of  which  enter  the  Danube. 

The  course  of  the  principal  streams  of  High  Europe  affords  a 
striking  illustration  of  the  fact,  that  the  direction  of  the  flowing  wa- 
ters is  governed  by  the  general  slope  of  the  mass  elevations  of  the 
continent,  and  not  by  the  mountain  ranges.  The  latter,  indeed,  form 
but  trifling  obstacles  in  the  path  of  streams,  often  causing  no  more 
than  a  small  deviation  from  their  general  course.    A  slight  swell  op- 


56 


DRAINAGE   OF  ASM   AND  EUROPE. 


erates  in  the  same  manner,  and  often  produces  as  great  an  effect,  as 
a  range  of  mountains.     (See  Coast  Swell,  on  map,  page  37.) 

From  the  Alps  the  land  descends  gradually  northward  to  the  Bal- 
tic Sea,  eastward  to  the  Black  Sea,  and  westward  to  the  Atlantic 
Ocean.  The  Danube,  rising  in  the  Black  Forest  Mountains,  follows 
the  general  eastward  slope,  passing,  through  transverse  gaps,  a  num- 
ber of  mountain 
ranges  lying  di- 
rectly across  its 
course. 

The  Rhine,  ris- 
ing in  the  central 
Alps,  follows  the 
slope  of  the  high- 
lands towards  the 
north.  It  crosses 
the  Swiss  Alps 
and  the  Jura,  by 
transverse  val- 
leys, forming  Lake 
Constance  be- 
tween them ;  then 
descends  the  lon- 
gitudinal valley 
between  the  Vos- 
ges  and  Black 
Forest  Moun- 
tains, rounds  the 
northern  terminus 
of  the  former,  and 
crosses,  nearly  at  right  angles,  the  plateau  of  the  lower  Rhine. 

The  head  waters  of  the  Rhone  cross  the  Swiss  Alps  and  the  Jura, 
descending  the  westward  slope  ;  but,  turned  aside  by  the  high  bor- 
der of  the  massive  plateau  of  central  France,  the  stream  descends 
the  longitudinal  valley  between  the  Ce'vennes  and  the  Western 
Alps,  to  the  Mediterranean. 

In  like  manner  the  Weser  and  the  Elbe,  rising  in  the  interior  ba- 
sins north  of  the  Alps,  traverse  the  secondary  continental  axis  and 
the  swells  which  intervene  between  it  and  the  northern  seas ;  while 
the  Oder  and  Vistula  cross  the  swells  only.  Each  departs  from  its 
original  northwesterly  course  in  crossing  these  barriers,  but  returns 
to  it  as  soon  as  the  obstacle  is  passed. 


VIEW    <>N    THE    KIII.NK. 


3.  Low  Europe.  The  European  plain,  unlike  the  great  interior 
plains  of  the  New  World,  is  highest  in  the  centre,  where  the  Valdai 
Plateau  is  about  800  feet  in  altitude,  with  hills  of  1,100  feet. 

Hence  its  streams,  instead  of  being  combined  into  a  few  great 
systems,  are  dispersed  in  separate  courses,  descending  the  slopes 
from  the  interior,  towards  the  four  cardinal  points.  These  diver- 
gent streams,  al 
enter  the  four  in- 
land  seas,  which 
border  upon  thi 
great  European 
plain  and  fori 
its  only  outlets. 

Low  Europe, 
with   more   e  x  ■ 
tended  plains,  has 
on    the   whol( 
longer  rivers  thai: 
H  igh  Europe. 
But  here,  also,  the 
central  swell  suf- 
fices to  prevent 
combination  of  the 
fl  o  w  i  n  g    waters 
into    one    great 
system   like    that 
of  the  Mississippi 
It  is  worthy  o 
remark,  that  th< 
longest  streams  o 
Europe,  and  those   draining   the   largest  areas,  are   nearly  all  di- 
rected towards  the  vast  depression  which  separates  that  continent 
from  Asia. 

4.  The  PENINSULAS  have  only  subordinate  streams.  The  longest 
are  those  of  Spain  which  descend  from  the  northeastern  highlands, 
near  the  Mediterranean  shores,  to  the  Atlantic  Ocean. 

In  the  Scandinavian  Peninsula  the  streams  mainly  enter  the  Bal- 
tic, the  fiords,  due  to  the  submergence  of  the  valleys,  taking  the 
place  of  rivers  on  the  Atlantic  slope.  In  the  transverse  valleys,  or 
the  eastern  slope  of  the  mountains,  are  many  beautiful  Alpine  lakes, 
some  of  which  are  of  considerable  size. 


IV.  Tables  of  Rivers  and  Lakes  of  Asia-Europe. 


Rivers  of  Asia. 


Obi  .  .  .  . 
Yenisei  .  .  . 
Yang-tse  kiang 
Lena  .  .  .  . 
Amoor  .  .  - 
Uoang-bo  . 
Brahmapootra  . 
Ganges     .    .     . 


Area  of  Ba- 

Length of 

sin  in  Eng 

Course  in 

sq.  miles. 

Eng.  miles. 

1,250,000 

3,000 

1,040,000 

3,400 

960,000 

3,320 

800,000 

2,700 

786,000 

2,650 

714,000 

2,800 

450,000 

2,300 

416,000 

1,600 

<0 

Rivers  of  Asia. 


Rivers  of  High  Europe. 


Danube 
Rhine  . 
Vistula 
Elbe  . 
Loire  . 
Rhone 
Po  .     . 


311,000 

1,800 

90,000 

880 

68,900 

650 

59,600 

800 

52,000 

660 

37,400 

550 

31,200 

460 

Indus   

Mekong     

Euphrates      .... 

Tarim 

Amoo  Daria  .... 

Irawaddy 

Sir  Daria 

Helmund 

Rivers  of  Low  Europe. 

Volga 

Dnieper 

Don 

Dwina 

Ural 

Petchora 

Duna 


Area  of  Ba> 

sin  in  Hi i!'" 
sq.  Miles. 


402,000 
400,000 
255,000 
235,000 
220,000 
140,000 
100,000 
80,000 


Length  of 
Course  in 
Eng.  miles. 


600,000 
180,000 
170,000 
130,000 
106,000 
100,000 
44,000 


1,850 
2,500 
1,750 
1,160 
1,260 
1,200 
1,200 
800 


2,000 
1,120 
1,100 
1,000 

970 
1,000 

flOO 


Lakes  of  Asia. 


Caspian  Sea     .     .    .    i 

Aral  Sea 

Baikal  Lake,  E.  Siberia 
Balkhash,  W.  Siberia 
Tengri-nor,  Thibet  . 
Tong-ting,  China  . 
Koko-nor,  Mongolia 
Urumia,  Armenia  . 
Kossogol ,  Mongolia  . 
Van,  Armenia  .  ■ 
Dead  Sea,  Palestine  . 
Sir-i-kol,  Pamir   .    . 


Area  iu 

Altitude 

Depth. 

sq.  miles 

in  feet. 

132,000 

-83 

2,700 

26,400 

36 

200 

15,200 

1,280 

3,000 

6,400 

600 

60 

3,500 

— 

— 

2,300 

— 

— 

2,000 

— 

— 

1,700 

4,350 

60 

1,500 

5,520 

— 

1,414 

5,470 

— 

500 

-1,286 

1,300 

40 

15,600 

— 

Lakes  of  Europe. 


Ladoga,  Russia 
Ouega        " 
Wener,  Sweden 
Wetter        " 
Maelar        " 
Balaton,  Hungary  . 
Hielmar,  Sweden    . 
Leman,  Geneva,  Switz'd 
Constance,  Switzerland 

Qarda 

Maggiore,  Italy  .     .     . 
Como,  Italy    .... 


Area  in 

Altitude 

sq.  miles 

in  feet. 

6,900 

50 

4,900 

237 

2,300 

143 

800 

289 

320 

6 

265 

469 

202 

76 

240 

1,226 

190 

1,263 

140 

237 

70 

686 

59 

697 

ANALYSIS   OF  SECTION  V. 

I.  Eastern  Asia. 

1.  Influence  or  Continental  Structurs. 

a.  Position  of  axes. 

b.  Waters  of  central  depression. 

c.  Waters  of  exterior  slopes. 


Depth. 


400 
38 


DRAINAGE   OF  AFRICA  AND   AUSTRALIA. 


57 


Principal  Streams. 

a.  Of  northern,  eastern,  and  southeastern  slopes. 

b.  Of  southern  and  western  slopes. 

c.  Of  central  depression. 


H.  Western  Asia. 

a.  Principal  system.    Stream  of  central  depression. 

III.  Europe. 

1.  Separate  Hydrographical  Centres. 

2.  High  Europe.  • 

a.  Four  Alpine  systems. 

b.  Secondary  systems  of  High  Europe. 

c.  Truth  illustrated  by  course  of  these  streams. 

Effect  of  mountain  ranges  and  swells. 

d.  Course  of  Danube.     Rhine.    Rhone. 

e.  Course  of  secondary  streams. 
3.  Low  Europe 

a.  Hydrographical  centre.     Result.     Course  of  rivers. 

b.  Streams  compared  with  those  of  High  Europe. 

IV.  Tables  of  Rivers  and  Lakes. 


VI.  — DRAINAGE   OF  AFRICA  AND  AUSTRALIA. 


I.  Africa. 

1.  Influence  op  Structure.  Africa  having,  like  the  Ameri- 
can continents,  its  axes  near  opposite  shores,  has  its  flowing  waters 
combined  in  the  interior  of  the  continent.  Five  principal  systems 
—  the  Nile,  the  Niger,  the  Congo,  the  Zamhesi,  and  the  Orange  — 
embrace  nearly  all  the  flowing  waters  of  the  continent ;  and  all  but 
the.  last  derive  their  water  wholly  from  the  tropical  region,  between 
20°  south  and  16°  north  latitude.  Each  is  especially  connected  with 
one  of  the  primary  regions  of  the  continental  structure. 

2.  The  Nile,  draining  the  west  slope  of  the  main  axis,  is 
the  most  characteristic  as  well  as  the  most  celebrated  of  African 
streams.  Its  main  sources  are  in  great  lakes,  near  the  equator, 
from  3,000  to  4,000  feet  above  the  level  of  the  sea ;  but,  in  its  mid- 
dle course,  it  receives  the  waters  of  eastern  Soudan  and  Abyssinia. 
This  part  of  the  course  is  characterized  by  the  famous  "  Cataracts 
of  the  Nile,"  the  last  of  which  occurs  at  Assuan,  at  the  entrance  of 
the  stream  into  Egypt. 

Below  the  Atbara  the  Nile  traverses  a  rainless  district  900 
miles  in  breadth,  within  which,  in  a  course  of  1,700  miles  from  the 
Mediterranean,  it  does  not  receive  a  single  tributary ;  and  its  valley 
is  a  narrow  belt  of  verdure  in  the  midst  of  a  burning  desert. 

The  fertility  of  this  narrow  valley  is  due  to  alluvial  soil  accumulated  during 
the  periodic  overflows  of  the  river.  This  wonderful  inundation  in  a  rainless 
region,  so  mysterious  to  the  ancient  world,  is  explained  by  the  fact  that,  though 
its  lower  course  is  in  temperate  latitudes,  all  the  sources  of  the  Nile  lie  within  the 
region  of  abundant  periodical  rains.  These  fall  copiously  on  the  sources  of  the 
White  Nile  about  the  time  of  the  equinoxes,  and  in  Abyssinia  a  little  later. 

The  Abyssinian  rains,  being  nearer  the  mouth,  cause  a  first  rise,  which  reaches 
Egypt  about  the  middle  of  June.  This  is  soon  followed,  and  increased  to  the  maxi- 
mum, by  the  rising  waters  of  the  White  Nile  ;  and  in  August  and  September  the 
flood  is  at  its  height.  By  the  middle  of  October  it  begins  to  abate  ;  in  November 
the  water  has  receded  sufficiently  to  permit  the  sowing  of  the  seed  in  the  fresh 
Baud.  In  December  all  the  valley  is  green  with  growing  crops,  and  the  harvests 
follow  iii  quick  succession. 

3.  Other  Systems.  The  Niger  drains  the  Kong  plateau. 
Starting  in  the  west,  from  the  highest  portion,  it  descends  successive 
terraces  to  the  interior  depression ;  then  turning  southward,  and 
reaching  the  sea  through  a  break  in  the  mountains,  it  forms  a  delta 
far  surpassing  in  extent  the  famous  delta  of  the  Nile. 

The  Congo,  draining  the  equatorial  portion  of  the  central  depres- 
sion, is  the  Amazon  of  Africa.  It  discharges,  into  the  Atlantic,  a 
volume  of  water  fully  three  times  that  of  the  Mississippi  ;    and  its 


powerful  current  is  perceptible  in  the  sea,  scores  of  miles  from  the 
mouth. 

The  Zambesi  drains  the  southern  part  of  the  central  depression, 
and  enters  the  Indian  Ocean.  In  its  middle  course  is  the  celebrated 
Victoria  Fall,  discovered  by  Dr.  Livingstone,  and  said  to  rival  in 
majesty  and  beauty  the  cataract  of  Niagara. 

The  Orange  River  drains  the  extreme  southern  plateau,  in  which 
the  continental  axes  meet.  Nearly  its  entire  course  lies  through  a 
table  land  from  4,000  to  5,000  feet  in  altitude. 


II.  Australia. 

No  continent  has  so  few  rivers  as  Australia.  The  Murray,  with 
its  great  tributaries,  the  Darling  and  the  Lachlan,  forms  the  only 
river  system  worthy  of  the  name.  Owing  to  the  great  irregularity 
of  the  rains,  most  other  rivers  have  no  permanent  existence  ;  but  are 
transformed,  in  seasons  of  drought,  into  a  series  of  disconnected, 
shallow  pools  or  lakes. 

III.  Table  of  African  and  Australian  Rivers  and  Lakes. 


Rivers. 

Basin  in 

Course  in 

Lakes. 

Area  in 

Altitude 

Lakes. 

Area  in 

Altitude 

Eng.  sq.  m. 

Kug.  m. 

sq.  miles 

in  feet. 

sq  miles 

in  feet. 

Nile 

1,425,000 

4,000 

Victoria,  Africa 

28,000 

4,300 

iMoero,  Africa 

3,000 

3,000 

Niger 

800,000 

3,000 

Albert,        " 

26,000 

2,700 

iTzana,      " 

1,000 

6,000 

Congo 

800,000 

— 

Tchad,         " 

15,000 

800 

Ngami,     " 

300 

2,800 

Zambesi 

900,0C0 

1,600 

Tanganyika" 

13,000 

2.800 

Eyre,   Aust'a 

3,000 

70 

Orange 

446,000 

1.000 

Xyassa,        " 

8,000 

1,300 

Gairdner  " 

2,400 

366 

Murray,  Aust. 

500,000 

1,500 

Bangweolo,  " 

5,000 

4,000 

Torrens,  u 

2,600 

— 

IV.  Conclusion. 

The  distribution  of  river  systems  shows  how  closely,  in  each  con- 
tinent, the  drainage  depends  upon  the  general  plan  of   structure. 

Farther,  we  observe  that  the  Atlantic  and  Arctic  Oceans,  toward 
which  all  the  long  continental  slopes  are  turned  (see  page  42,  IX., 
and  Map,  page  63),  receive,  either  directly  or  through  inland  seas, 
three  fourths  of  all  the  continental  waters,  including  the  greatest 
streams  of  the  globe.  The  Pacific  and  Indian  Oceans,  covering 
nearly  half  of  the  Earth's  surface,  receive  but  the  remaining  fourth  ; 
and  among  these  only  the  three  streams  of  Eastern  Asia  hold  the 
first  rank  in  regard  to  length  of  course  and  extent  of  basin. 


ANALYSIS  OF   SECTION   VI. 

I.  Africa. 

1.  Influence  op  Structure. 

a.  Position  of  axes. 

b.  Source  and  connections  of  systems. 

2.  Nile  System. 

a.  Region  drained  by  it. 

b.  Main  sources.    Accessions  in  middle  course. 

c.  Peculiarities  of  lower  course. 

d.  Valley,  source^fertility. 

e.  Inundations.     Cause.     Progresi 

3.  Other  African  Systems.        '  # 

a.  Niger.    Region  drained  by  it.    Course 

b.  Congo.    Zambesi. 

c.  Orange. 


Termination. 


II.  Australia. 

a.  Comparative  number  of  streams.     Principal  system. 

b.  Character  of  other  streams. 

III.  Tabic  of  IMvers. 

IV.  Conclusion. 


58 


THE  SEA. 


THE   SEA. 


L  — INTRODUCTION. 

I.  Sea  Water. 

1.  Its  Composition.  The  water  of  the  sea  contains  in  solution 
a  large  amount  of  common  salt  (chloride  of  sodium),  and  smaller 
proportions  of  sulphate  and  carbonate  of  lime,  magnesia,  pot- 
ash, iodine,  and  some  other  substances.  It  is  estimated  that  they 
constitute  about  one-thirtieth  of  the  entire  weight  of  sea  water. 

In  the  open  ocean  the  composition  of  the  water  is  nearly  uniform, 
though  about  20°  north  latitude,  and  16°  south,  there  is  a  slightly 
greater  proportion  of  saline  matter  than  elsewhere. 

Some  inclosed  arms  of  the  sea,  in  or  near  tropical  regions  —  like 
the  Mediterranean  and  the  Red  Sea  —  evaporating  more  water  than 
they  receive  by 
rivers,  and  having 
i  n  consequence  a 
constant  influx  of 
sea  water,  are  more 
salt  than  the  ocean. 

Others,  like  the 
Black  and  Baltic 
Seas,  receiving 
more  water  by 
r  i  v  ers  than  they 
evaporate,  and  dis- 
charging the  excess 
into  the  sea,  are  less 
salt  than  the  ocean. 

2.  The  tempe- 

EATUKE   of    the 

ocean,  at  and  near 
the  surface,  varies 
with  the  latitude, 
from  an  average  of 
80°  Fahr.  within 
the  tropics,  to  near 
the  freezing  point 
in  the  polar  re- 
gions, where  ice  is  to  be  found  in  the  sea  at  all  seasons  of  the  year. 

Below  a  certain  depth,  which  varies  with  the  latitude,  the  tempe- 
rature is  nearly  uniform,  at  from  33|°  to  35°  Fahr.,  about  equal  to 
the  average  temperature  of  the  surface  waters  in  latitude  60°. 

In  lower  latitudes,  as  the  climate  becomes  warmer,  this  low  tem- 
perature is  found  at  constantly  increasing  depths  ;  until,  at  the 
equator,  it  is  reached  only  about  10,000  feet  below  the  surface. 
Towards  the  poles,  also,  where  the  climate  is  colder,  the  line  of  uni- 
form temperature  rapidly  sinks  ;  and  in  latitude  70°  it  is  found  at 
the  depth  of  about  4,000  feet. 

Thus  it  appears  that  within  60°  of  the  equator  the  deep  waters  are 
colder  than  the  surface,  while  beyond  that  latitude  they  are  warmer. 

The  salt  of  the  ocean  tends  to  preserve  its  liquid  condition  at  low 
temperatures.  Sea  water  freezes  only  when  the  temperature  is  re- 
duced to  26£°,  while  the  freezing  point  of  fresh  water  is  32°  Fahr. 

II.  Marine  Life. 

The  ocean  supports  an  inconceivable  variety  of  animal  life.     Its 


iUBMAKINE    LIFE   LN   THE   NORTHERN   SEAS. 


inhabitants  vary  in  size,  from  the  gigantic  whale  to  animals  too 
small  to  be  perceived  by  the  unaided  eye  ;  and  in  organization,  from 
the  mammal  to  the  formless,  jelly-like  mass,  floating  upon  the  sur- 
face of  the  water. 

It  is,  perhaps,  not  equally  rich  in  vegetable  life  ;  but  plants  in 
great  variety,  some  of  which  are  exceedingly  beautiful  in  form  and 
color,  are  found,  both  attached  to  rocks  in  the  shallow  waters  adja- 
cent to  the  shores,  and  floating  in  mid  ocean.  Immense  fields  of  sea 
weed,  covering  thousands  of  square  miles,  occur  in  those  portions  of 
the  ocean  not  disturbed  by  the  general  currents.  The  most  remark- 
able of  these  is  the  Sargasso  Sea,  near  the  Tropic  of  Cancer,  in  the 
Atlantic  Ocean. 

III.  Bottom  of  the  Sea. 

The  bottom  of  the  sea,  as  far  as  known,  is  less  irregular  than 

the   surface   of  the 
continents,  but   its  | 
variations   of    level 
are  on   a   much 
grander  scale. 

It  is  convex,  like  ! 
the   surface  of   the 
sea,  being  a  vast  j 
area  of  the  Earth's  j 
crust  slightly  de-  j 
pressed    below  the  1 
regular  curve  of  the 
sphere  ;    while  the 
continents    are] 
smaller    areas,  ele-J 
v  a  t  e  d     somewhat 
above  this  curve. 

On  these  depres- 
sions, the   waters,  \ 
originally    covering  \ 
the   entire,    surface 
of  the  sphere,  have  j 
collected,    in    obe- 
dience to  the  law  of 
gravity,   filling   up 

the  irregularities  in  the  spherical  outline,  and  forming  the  oceans. 
This  convexity  of  the  sea  bottom  is  clearly  illustrated  by  the  Sections  of  the 

Atlantic  Basin,  page  60. 


ANALYSIS  OF  SECTION  I. 


I.  Sea  Water. 


1.  Its  Composition. 

a.  Substances  in  solution. 

b.  Waters  in  open  ocean. 

c.  Waters  in  inclosed  seas. 

2.  Tempeeatube. 

a.  At  and  near  the  surface. 

b.  Temperature  of  deep  waters. 

c.  Temperature  of  depths  towards  the  equator. 

d.  Temperature  of  depths  towards  the  poles. 

e.  Deep  waters  compared  with  surface. 

f.  Freezing  point  of  sea  water. 


II.  Marine  life. 


a.  Animal  life. 

b.  Vegetable  life. 

c.  Examples  of  mariue  vegetation- 


IJT.  Rottom  of  Sea. 


a.  Nature  of  its  surface. 

b.  Relation  to  spherical  outline. 

c.  Why  covered  with  waters  of  globe. 


THE  OCEANS. 


59 


II.  — THE  OCEANS. 


The  Basins  of  the  Oceans. 

1.  Their  Sepabation.  The  waters  of  the  sea  are  separated  by 
(foe  lands  into  three  great  oceans,  which  are  the  counterparts  of  the 
land  masses.  The  Pacific,  the  Atlantic,  ancLthe  Indian  Ocean,  cor- 
respond to  the  three  pairs  of  continents  in  which  the  lands  are 
grouped  (See  p.  21,  II.),  and  separate  them  one  from  another. 

The  Atlantic  and  the  Pacific  are  subdivided,  each  having  a  north- 
ern and  a  southern  basin,  corresponding  to  the  northern  and  the 
southern  continents.  The  Indian  Ocean  has  only  a  southern  basin  ; 
but  the  vast  depression  between  Asia  and  Europe,  in  the  bottom  of 
which  lie  the  Caspian  and  Aral  Seas,  may  be  considered  as,  in  a  cer- 
tain sense,  its  complement. 

The  Arctic  Ocean  is  properly  a  continuation  of  the  Atlantic ;  but, 
surrounded  as  it  is  by  the  coasts  of  the  three  northern  continents,  it 
has  a  physiognomy  of  its  own.  The  Antarctic,  also,  is  not  properly 
a  separate  ocean,  but  is  the  common  centre  from  which  the  three 
great  basins  radiate. 

2.  Their  Forms  and  Sizes.  Each  of  the  three  great  oceans  is 
broadest  at  the  south,  and  gradually  narrows  towards  the  north ; 
hence  their  general  figure  is  the  opposite  of  that  of  the  continental 
masses. 

The  Pacific  is  oval  in  outline,  and  broadly  open  at  the  south  ;  but 
it  is  nearly  closed  at  the  north,  the  opposite  shores  converging  so 
that  only  the  narrow  passage  of  Behring  Straits  connects  this  ocean 
with  the  Arctic. 

This  vast  basin  contains  more  than  half  of  the  waters  of  the  entire 
sea.  Its  extent,  its  compact  form,  and  the  direction  of  its  greatest 
elongation  from  southeast  to  northwest,  makes  it  the  counterpart  of 
Asia-Europe,  the  dominant  mass  of  the  Old  World. 

The  Atlantic  basin,  which  has  only  about  one  half  the  area  of  the 
Pacific,  has  been  likened  by  Humboldt  to  a  long  valley,  with  approx- 
imately parallel  sides.  This  is  the  only  basin  widely  open  at  the 
north  ;  and,  stretching  from  pole  to  pole,  it  forms  the  only  complete 
channel  for  the  interchange  of  polar  and  equatorial  waters.  By  its 
narrow,  slender  form,  and  its  direction  from  north  to  south,  it  forms 
the  counterpart  of  the  New  World. 

The  Indian  Ocean,  which  has  a  triangular  outline,  has  no  commu- 
nication with  the  northern  waters.  It  finds  its  counterpart  in  Africa, 
like  itself  compact  in  outline,  and  almost  destitute  of  projecting 
members. 

3.  Their  Branches.  The  three  great  ocean  basins  differ  in 
regard  to  the  position  and  character  of  the  branches,  by  which  the 
coasts  of  the  continents  are  indented,  each  being  distinguished  by  a 
particular  class  of  coast  waters. 

Coast  waters  may  be  classified,  according  to  their  form  and  their 
position  in  respect  to  the  adjacent  lands,  as  inland  seas,  border  seas, 
and  gulfs  or  bays. 

The  first  lie  within  the  general  figure  of  the  continent,  being  en- 
closed by  peninsulas,  as  the  Baltic  Sea;  or  between  adjacent  conti- 
nents, as  the  Mediterranean  and  Red  Seas.  (See  Map,  pages  28, 
29.) 

The  second  lie  without  the  continental  figure,  and  are  separated 
from  the  main  ocean  by  islands,  as  the  Caribbean  Sea.  The  third 
are  simple  bends  in  the  coast  line,  without  separation  from  the  ocean 
basin,  as  the  Gulf  of  Bengal. 

The  Atlantic  is  the  most  branching  of  the  oceans.  It  has  all  the 
forms  of  coast  waters  just  described,  but  is  especially  distinguished 


by  the  number  and  great  size  of  its  inland  seas.  Two  of  these,  the 
Mediterranean  Sea  and  the  Gulf  of  Mexico,  lie  in  the  warm  regions  ; 
and  two,  Hudson  Bay  and  the  Baltic  Sea,  in  colder  latitudes. 

The  border  seas  are  represented  by  the  Caribbean  Sea,  within  the 
tropics,  and  the  Gulf  of  St.  Lawrence  and  the  North  Sea,  in  tem- 
perate latitudes.  The  Gulf  of  Guinea,  and  the  Bay  of  Biscay,  are 
examples  of  the  third  class  of  coast  waters,  in  the  Atlantic. 

The  Pacific  is  particularly  rich  in  vast  border  seas,  a  continuous 
series  of  which  lines  the  Asiatic  and  Australian  coasts.  Among 
these  are  the  Behring  Sea,  inclosed  by  the  peninsula  of  Alaska  and 
the  Aleutian  Islands  ;  Okhotsk  Sea,  inclosed  by  Kamchatka  and 
the  Kurile  Islands ;  the  Sea  of  Japan,  and  the  North  and  South 
China  Seas  ;  and  the  Arafura,  Coral,  and  New  Zealand  Seas,  on  the 
Australian  coast. 

Only  two  inland  seas  of  considerable  size  —  the  Gulf  of  Califor- 
nia, in  North  America,  and  the  Yellow  Sea,  in  Asia  —  mark  this 
entire  basin. 

The  Indian  Ocean  is  characterized  by  gulfs,  two  of  which  form 
the  entire  northern  extension  of  the  basin,  namely  :  the  Gulf  of  Ben- 
gal, and  the  Arabian  Sea.  It  has  also  two  inland  seas  of  consider- 
able extent,  the  Red  Sea  and  the  Persian  Gulf,  isolating  the  penin- 
sula of  Arabia  from  the  adjacent  continents  ;  but  border  seas  are 
wholly  wanting  in  the  Indian  Ocean. 

4.  Their  Islands.  The  Pacific  is  far  richer  than  the  other 
oceans  in  both  continental  and  oceanic  islands.  The  most  extensive 
continental  archipelago  on  the  globe,  is  formed  by  the  multitude  of 
islands  lying  between  Asia  and  Australia.  Successive  series  of  conti- 
nental islands  skirt  the  entire  eastern  coast  of  Asia  and  Aus- 
tralia ;  and  nowhere  is  found  a  parallel  to  the  multitude  of  oceanic 
islands  which  are  spread  over  the  central  portions  of  this  basin.  (See 
Map,  page  18.) 

The  Atlantic  possesses  —  in  the  Antilles,  the  British  Isles,  and  the 
islands  of  the  Mediterranean  —  continental  archipelagoes  of  great 
importance ;  but  its  oceanic  islands  are  limited  to  the  groups  of  the 
Bermuda,  Azores,  Madeira,  Canary,  and  Cape  Verd  Islands,  with 
St.  Helena  and  a  few  other  isolated  volcanic  islands. 

The  Indian  Ocean  has  comparatively  few  islands  of  either  class. 
Madagascar,  Ceylon,  and  Socotora,  represent  the  continental  islands  ; 
the  Laccadives  and  Maldives,  with  here  and  there  a  few  volcanic 
islands,  as  Bourbon  and  Mauritius,  make  up  the  oceanic. 

II.  Tlie  Beds  of  the  Ocean. 

1.  Extent  of  our  Knowledge.  Little  is  known,  in  detail,  in 
regard  to  the  conformation  of  the  bottom  of  the  sea.  But  numerous 
soundings,  both  in  shallow  shore  waters  and  in  the  deep  sea,  have 
given  us  an  approximate  idea  of  the  nature  of  the  beds  of  the  Atlan- 
tic Ocean,  the  Mediterranean  Sea,  the  Indian  Ocean,  and  the  Red 
Sea. 

2.  The  Atlantic  Bed.  The  Atlantic  basin  is,  in  general, 
deeper  on  the  side  of  the  New  World.  The  deepest  portions,  so  far 
as  known,  form  a  great  trough,  in  three  parts,  which  are  severally 
parallel  to  the  eastern  shore  of  North  America  and  the  northern 
and  eastern  shores  of  South  America. 

The  bed  of  the  North  Atlantic  seems  to  consist  of  two  parallel 
valleys  —  the  western  about  18,000  feet  in  average  depth,  the  east- 
ern about  13,000  —  separated  by  a  swell  less  than  10,000  feet  deep. 
(See  Fig.  25.)  Both  valleys  become  less  deep  towards  the  north, 
but  are  still  distinguishable  in  the  so  called  "  Telegraph  Plateau," 
between  Newfoundland  and  Ireland.     (See  Fig.  26.) 


60 


THE   OCEANS. 


FIG.   25.      SECTION   OF  THE   ATLANTIC    BASIN   FROM    CAPE    ST.    ROQUE,    BRAZIL,    TO    CAPE   PALMAS,    WESTERN   AFRICA. 


In  the  latitude  of  Iceland,  whose  volcanic  mass  rises  from  the 
northern  terminus  of  the  dividing  swell,  the  eastern  valley  is  oblit- 
erated, the  depth  of  the  sea  between  this  island  and  the  European 
shore  scarcely  averaging  1,500  feet.  The  western  valley  pre- 
serves a  depth  of  8,000  or  9,000  feet  as  far  as  Greenland,  where  it 
divides,  its  two  branches  extending  to  the  Arctic,  on  opposite  sides 
of  Greenland. 

The  accompanying  profiles  show,  in  fathoms,  the  depths  of  the  Atlantic  in  equa- 
torial regions  (Fig.  25),  where  the  dividing  swell  is  distinctly  perceptible ;  and 
along  the  line  of  the  survey  for  the  first  Atlantic  cable  (Fig.  26),  where,  though 
less  apparent,  it  still  exists. 

Near  the  continents  the  sea  is  often  shallow,  the  bottom  seeming 
to  be  only  an  extension,  by  gentle  slopes,  of  the  adjacent  lands. 

Along  the  American  shores,  in  the  latitude  of  New  York,  the  depth, 
for  a  distance  of  more 

,,  1  AA       *1         '     1  Cape  St.  Roque.  Length,  1760  nautical  miles. 

than  600  feet ;  then 
suddenly  the  bed  de- 
scends,by  a  steep 
slope,  to  the  depth  of 
6,000  or  9,000  feet. 
After  a  comparatively 

narrow  interval,  a  second  terrace  descends  to  the  main  basin,  from 
15,000  to  18,000  feet  deep. 

These  regular  variations  of  level,  and  the  absence  of  any  oceanic 
islands  other  than  the  volcanic  and  coral  islands,  disprove  the  idea, 
often  advanced,  that  the  bed  of  the  oceans  is  like  the  surface  of  a 
submerged  continent,  covered  with  mountain  chains  and  valleys.  It 
seems  far  more  uniform,  extensive  plains  and  huge  table  lands  being 
its  predominating  features.  Mountain  chains  are  found  only  near 
the  continents,  as  parts. of  the  continental  structure;  and  when 
reaching  above  the  surface  of  the  sea  they  form  chains  of  continental 
islands. 

3.  The  Pacific  and  Indian  Oceans.  The  Indian  Ocean,  — 
according  to  soundings  made  in  laying  telegraphic  cables,  from  Aden 
to  Bombay,  and  from 
Madras  to  the  Malay 
peninsula,  —  is  quite 
similar  to  the  Atlan- 
tic in  the  general  fea- 
tures of  its  bed. 

A  regular  valley, 
having  an  average 
depth  of  12,000  feet, 

lies  between  Africa  and  India,  its  eastern  margin  being  about  200 
miles  from  Bombay,  whence  a  submarine  plateau,  but  a  few  hun- 
dred feet  deep,  extends  to  the  peninsula. 

East  of  India  is  a  similar  valley  from  12,000  to  14,000  feet  deep. 
It  terminates,  near  the  shores  of  Sumatra,  in  a  submarine  plateau, 
less  than  250  feet  below  the  surface,  which  forms  the  base  of  the  isl- 
ands in  the  great  Indian  Archipelago,  between  Asia  and  Australia. 

The  chain  of  coral  islands,  —  the  Laccadives,  the  Maldives,  and 
the  Chagos  Archipelago  (See  map,  page  18),  —  extending  south- 
ward through  the  central  part  of  the  Indian  Ocean,  seems  to  indi- 
cate the  presence  of  a  submarine  dividing  ridge  in  this  basin,  similar 
to  that  separating  the  two  valleys  of  the  Atlantic. 

Occasional  soundings  in  the  southwestern  part  of  this  ocean,  in- 
dicate depths  equal  to  the  maximum  in  the  Atlantic  basin. 

The  bed  of  the  Pacific  is  much  less  known  than  that  of  the  At- 
lantic and  Indian  Oceans.     In  the  absence  of  soundings,  of  which 


Cape  Palmas. 


Newfoundland. 


FIG.  26. 


few  have  been  made,  its  average  depth  has  been  calculated  from 
the  velocity  of  the  tide-wave  and  earthquake  waves  crossing  it,  which 
depends  upon  the  depth  of  the  basin  in  which  the  waves  move. 

Prof.  Bache,  late  Superintendent  of  the  United  States  Coast  Sur-j 
vey,  estimates,  in  this  way,  the  depth  between  Japan  and  California 
at  from  12,000  to  14,000  feet.  A  calculation  by  Prof.  HochstetterJ 
based  on  the  movement  of  the  waves  raised  by  the  great  earthquake! 
of  1868,  gives  11,500  feet  as  the  depth  of  the  sea  between  the  Soutli 
American  coast  and  the  Chatham  Islands,  east  of  New  Zealand! 
The  central  part  of  the  South  Pacific  basin,  however,  is  probably1 
much  deeper  than  this. 

4.  Inland  and  Bokdek  Seas.  These  inclosed  basins  belong 
to  the  structure  of  the  continents,  rather  than  to  the  oceans.    All  are 

of  slight  depth,  ex-j 
cept  those  lying  with-] 
in  the  transverse  zone: 
of  fracture1;  and 
even  these  are  shal- 
low in  comparison1 
with  the  great  basins, 
with  which  they  ard 
connected,  as  is  apparent  from  the  depths  given.below. 

The  Gulf  of  Mexico  is  from  5,000  to  1000  feet  in  depth.  The  deepest  pari 
of  the  Caribbean  Sea,  on  a  line  connecting  Porto  Rico  and  Costa  Rica,  average! 
7,000  feet ;  and  near  the  latter  it  reaches  a  depth  of  14,000 ;  but  the  ocean,  imme- 
diately outside  of  the  Lesser  Antilles,  is  more  than  18,000  feet  deep. 

The  Mediterranean  is  divided  into  two  basins,  by  a  rocky  isthmus,  from  50  to] 
500  feet  below  the  surface,  lying  between  Sicily  and  Cape  Bon,  in  Africa.  The] 
western  basin  is  over  9,000  feet  in  depth,  and  comparatively  uniform  ;  while  thej 
eastern  is  more  irregular,  varying  from  6,000,  near  the  centre,  to  13,000  feet,  soutli 
of  the  Ionian  Islands.  The  Red  Sea  has  an  irregular  bottom,  with  an  averagJ 
depth  of  3,000  feet,  but  in  some  places  it  reaches  6,000. 

The  Baltic  Sea,  being  a  simple  depression  in  the  great  European  plain,  is  bufl 
a  few  hundred  feet  deep.  In  the  North  Sea,  the  depth  averages  300  feet,  and 
rarely  exceeds  600.  The  continent  is  here  prolonged  in  the  form  of  a  submarini 
plain,  whose  highest  portions  form  the  British  Isles.     (See  page  38.) 

The  Border  Seas  oM 
Length,  1670  nautical  miles.  Valentia,  Ireland.  ,4 gja,  lying   within    the 

chain  of  continental  isl-  j 
ands,  are  only  a  few  hunfl 
dred  feet  in  depth,  whilfl 
immediately  without  thosJ 
islands,  abrupt  slopes  dca 
scend  to  the  great  depths 
of  the  Pacific  basin. 

5.  The  greatest 
depths  thus  far  found  in  the  ocean  basins,  have  been  reported  from] 
the  South  Atlantic.  Captain  James  Ross  reports  a  sounding,  wesB 
of  St.  Helena,  of  27,000  feet,  without  touching  bottom.  Captai™ 
Denham  and  Captain  Parker  report,  severally,  46,000  and  50,00^ 
feet,  west  of  the  island  of  Tristan  da  Cuiiha ;  but  owing  to  the  din 
ficulty  of  obtaining  accurate  soundings  in  great  depths,  these  figured 
can  hardly  be  accepted  as  conclusive. 

Observations  thus  far  made  justify  the  conclusion  that  the  greatS 
est  depths  of  the  sea  are  from  25,000  to  30,000  feet,  about  equivaf 
lent  to  the  greatest  heights  upon  the  continents. 

But  rightly  to  understand  the  magnitude  of  these  features  of  rej 
lief,  it  must  be  remembered  that  mountain  tops  are  but  isolated! 
points,  much  above  the  general  level  of  the  mass  of  the  emerged] 
lands ;  while  the  greatest  depths  of  the  oceans  are,  doubtless,  com  mo: 


»*o 


SECTION   OF  THE  ATLANTIC    BASIN   FROM    NEWFOUNDLAND  TO   VALENTIA    ISLAND,    ON   THE    LINE   OF   THE 

TELEGRAPH  CABLES. 


1  See  page  21,  Topic  II.,  3. 


WAVES   AND   TIDES. 


61 


to  extensive  surfaces,  which  are  the  counterparts  of  the  continental 
plains  and  table  lands. 


ANALYSIS   OP   SECTION   II. 


I.  Ocean  Basiim. 

1. 

Their  Sep.* 

RATION. 

:i 

Three  great  basins. 

Pacific,  Atlantic,  Indian. 

b 

Arctic  basin. 

c. 

Antarctic  basin. 

2. 

Form  and  Size. 

a. 

Common  feature. 

b 

Pacific  basin. 

Form.     Amount  of  water.       * 
Resemblance  to  Old  World. 

c. 

Atlantic  basin. 

Form.     Extent. 
Resemblance  to  New  World. 

d 

Basin  of  Indian  Ocean. 

i. 

Extensions 

on  Continental  Coasts. 

a. 

How  classified- 
Inland  seas. 
Border  seas. 
Gulfs  and  bays. 

b 

Atlantic. 

Characteristic  coast  basins. 
Other  forms  of  coast  basins. 

c. 

Pacific. 

d 

Indian. 

4 

Islands 

a. 

Pacific.     Relative  number.     Examples. 

b. 

Atlantic.     Relative  number.     Examples. 

c. 

Indian.     Relative  number.     Examples. 

Hm  Ocean  Beds. 

1. 

Extent 

OP 

our  Knowledge  op  them. 

2 

Atlantic  Bed. 

a. 

Of  what  consisting. 

Depth  of  valleys  and  dividing  swell 
Change  of  level  northward. 

b 

Depth  of  shores  and  successive  terraces. 

c 

Conclusion  from  observed  variations  of  bed. 

3.  Beds  OF 

Indian  and  Pacific  Oceans. 

a, 

Indian  Ocean.- 

Resemblance  to  Atlantic  bed. 
Bed  between  Africa  and  India. 
Bed  east  of  India 
Other  parte  of  bed. 

b 

Pacific  bed. 

Mode  of  ascertaining  its  depth- 
Results  of  calculations. 

4. 

Inland 

urn 

Border  Seas. 

a. 

General  character  as  to  depth. 

b. 

Gulf  of  Mexico  and  Caribbean  Sea. 

c. 

Mediterranean.     Red  Sea. 

d. 

Baltic 

e. 

North  Sea. 

f. 

Border  seas  of  Asia. 

5. 

Greatest  Ocean  Depths. 

a. 

Where  supposed  to  be. 

b. 

Depths  reported. 

a, 

Reported  figures  to  be  regarded  how. 

III.  — WAVES   AND    TIDES. 

I.  Oceanic  Movements. 

The  waters  of  the  :;ea  are  subject  to  various  kinds  of  motion,  due 
both  to  atmospheric  and  astronomical  causes.  Chief  among  them 
are  waves,  tides,  and  marine  currents. 


II.  Waves. 

Waves  are  the  alternate  rise  and  fall  of  successive  ridges  of  water. 
They  result  from  a  disturbance  of  the  equilibrium  of  the  surface 
waters,  by  the  action  of  the  wind,  and  affect  the  sea  only  to  a  mod- 
rate  depth. 

•  Waves  vary  in  height,  extent,  and  rapidity  of  progress,  according 
;o  the  force  of  the  wind,  the  depth  of  the  water,  and  the  extent  of 


the  basin  in  which  they  occur.     They  are  much  larger,  and  advance 
more  rapidly,  in  the  open  sea  than  in  inland  basins. 

The  advance  of  the  wave  is  the  communication  of  the  wave  move- 
ment to  successive  portions  of  the  sea ;  and  not,  to  any  considerable 
extent,  except  in  shallows,  an  onward  movement  of  the  water  itself. 
Thus  a  body  floating  upon  the  surface  of  the  sea  may  be  seen  repeat- 
edly rising  and  falling  with  the  waves,  with  but  a  slight  change  of 
position. 

When  waves,  advancing  towards  the  shore,  reach  the  shallows,  the 
motion  is  retarded  at  the  bottom  by  friction  ;  and  the  top,  moving 
on  without  support,  curls  over  and  breaks  in  foam  upon  the  beach  ; 
or,  in  very  shallow  seas,  it  may  break  at  a  considerable  distance  from 
the  shore. 

After  the  wind,  which  disturbed  the  surface,  has  subsided,  the  wa- 
ter continues  to  undulate  with  a  gentle  motion,  called  the  swell. 
This  seldom  ceases  entirely  before  a  fresh  storm  arouses  the  waves 
anew. 

III.  Tides. 

1.  Tides  are  movements  similar  in  character  to  waves,  but  differ- 
ing in  their  cause,  extent,  and  the  regularity  of  their  occurrence. 

Tides  are  caused  by  the  action  of  the  Sun  and  Moon  upon  the 
Earth  ;  they  affect,  therefore,  the  ocean  to  its  greatest  depths,  and 
throughout  its  entire  extent ;  and  they  occur  with  unvarying  regu- 
larity, the  water,  in  every  part  of  the  ocean,  rising  and  falling  alter- 
nately through  periods  of  about  six  hours  each.  Each  period  is  fol- 
lowed by  an  interval  of  a  few  moments,  during  which  the  water 
remains  at  the  level  it  has  just  attained. 


LOW  WATER. 


MOON. 


o 


LOW  WATER. 

FIG.    27.      PRODUCTION  OF  TIDAL  WAVE. 

The  period  of  rising  water  is  called  flood  tide,  that  of  receding 
water,  ebb  tide.  The  level  attained  at  the  close  of  flood  tide  is  called 
high  water,  or  high  tide  ;  and  that  at  the  close  of  ebb  tide,  low  wa- 
ter. The  interval  between  two  consecutive  high  tides  or  low  tides  is 
twelve  hours  and  twenty-six  minutes  ;  hence  high  water,  or  low  wa- 
ter, occurs  about  fifty-two  minutes  later  each  successive  day. 

2.  Mode  of  Production  of  Tides.  The  Moon,  notwithstand- 
ing its  smaller  mass,  has,  on  account  of  its  greater  nearness  to  the 
Earth,  an  influence  in  the  production  of  the  tides  which  is  more  than 
double  that  of  the  Sun  (as  100  to  30).  The  solar  tides,  being  so 
much  less  marked,  and  chiefly  merged  in  or  overpowered  by  the 
lunar  tides,  are  of  secondary  importance.  The  phenomena  of  the 
tides  must,  therefore,  be  explained  mainly  by  reference  to  the  latter. 

Tidal  Waves.  The  Moon  attracts  both  the  land  and  the  sea ;  but 
the  particles  of  the  latter  being  free  to  move,  the  waters  are  drawn 
towards  the  attracting  body  ;  and,  where  its  influence  is  most  power- 
ful, are  lifted  up  above  the  normal  curve  of  the  surface  of  the  sea. 

Thus  is  formed  a  vast  swell,  or  tide  wave,  upon  the  hemisphere 
turned  towards  the  Moon.  The  flowing  of  the  more  distant  waters 
towards  the  crest  of  this  wave,  causes,  on  each  side  of  it,  a  depres- 


62 


WAVES   AND  TIDES. 


FIG.   28. 


sion  of  the  surface,  or  low  water,  which  occurs  about  90°  from  the 
line  of  high  water.     (See  Fig.  27.) 

On  the  opposite  side  of   the  Earth    the  equilibrium  of   the  sea 
is  equally  disturbed,  and  the  same  cause  produces  a  second  wave, 
the  formation  of  which  is  explained  as  follows :  The  waters  most 
distant  from  the  attracting  body  being  least  affected  by  it,  their 
weight  is  somewhat  lessened,  and  they  are  less  attracted  towards  the 
centre  of  the  Earth  than  those  on  the  sides.     To  restore  the  equilib- 
rium, the  waters  on  the  sides,  which  exert  a  greater  pressure,  tend 
to  move  towards  the  region  of  least  attraction  and  their  accumulation 
there  raises  the  surface  of  the 
sea  slightly  above   its  normal 
level,  producing  the  second,  or 
counter  wave. 

Two  area*  of  high  water, 
therefore,  occur  simultaneously 
upon  the  Earth,  180°  distant 
from  each  other,  the  one  under 
the  Moon,  and  the  other  on  the  opposite  side  of  the  globe. 

Two  areas  of  low  water  occur  at  the  same  time,  midway  between 
those  of  high  water.  Owing  to  the  rotation  of  the  Earth  upon  its 
axis,  bringing  all  longitudes  successively  under  and  opposite  the 
Moon,  this  permanent  system  of  waves  and  troughs  travels  from 
east  to  west  over  every  part  of  the  sea.  This  occasions  the  regular 
succession  of  rising  and  falling  waters,  at  equal  intervals  of  time, 
occurring  along  all  coasts,  and  known  to  us  as  the  tides. 

3.  Spring  Tides.  The  attraction  of  the  Sun  causes  a  similar,  though  less 
strongly  marked,  system  of  four  daily  tides.  As  the  relative  positions  of  the 
Earth,  the  Sun,  and  the  Moon  are  constantly 
changing,  the  solar  and  lunar  tides  do  not  usu- 
ally coincide.  Twice  a  month,  however,  at  new 
and  full  Moon,  the  three  bodies  are  in  a  line  (as 
shown  in  figure  28). 

At  these  periods,  the  Sun  and  Moon  act  to- 
gether ;  and  an  unusually  high  water  is  produced 
which  is  the  sum  of  the  solar  and  the  lunar  high 
tide.  This  is  called  the  spring  tide.  Low  water 
at  this  period  is  correspondingly  lower  than  at 
any  other,  as  high  water  is  higher. 

At  the  first  and  third  quarters  of  the  Moon, 
the  three  bodies  are  so  situated  relatively  to  one 
another  (see  Fig.  29),  that  the  attractive  power 
of  the  Sun  upon  the  Earth  is  exerted  at  right  an- 
gles to  that  of  the  Moon,  thus  diminishing  the 
effect  of  the  latter.  High  -water  is  then  below, 
and  low  water  above,  its  ordinary  level.  These 
are  the  neap  tides. 

The  highest  tides  occur  when  the  luminaries 
are  nearest,  and  pass  most  nearly  vertically  on 
the  place  of  observation.  The  highest  of  the 
spring  tides  occur  in  March,  some  time  before  the 

vernal,  and  in  September,  some  time  after  the  autumnal  equinox,  when  the  Sun, 
being  vertical  at  the  Equator,  and  the  Moon  nearest  to  the  Earth,  the  equatorial, 
parent  wave  is  highest.    Thus  the  tides  have  daily,  monthly,  and  annual  periods. 

IV.  Course  of  Tidal  Waves. 

1.  Introduction.  If  the  ocean  covered  the  whole  Earth  with 
a  uniform  depth  of  water,  the  tidal  waves,  with  their  long  crests  ex- 
tending from  north  to  south,  would  follow  the  apparent  course  of  the 
Moon,  passing  from  east  to  west  entirely  around  the  globe.  They 
would  be  highest  in  the  equatorial  regions,  and  would  there  move 
with  the  velocity  of  more  than  1,000  miles  an  hour. 

The  continents,  which  divide  the  sea  into  three  great  basins,  op- 


pose the  passage  of  the  tidal  wave,  and  it  is  subjected  to  great  modi- 
fications in  each  ocean. 

The  velocity  with  whi :h  the  wave  advances  depends  upon  the  size 
and  form  of  the  ocean  in  which  it  moves,  the  depth  of  the  water,  and 
the  absence  of  obstacles  to  its  progress.  The  southern  half  of  the 
Pacific  presents  the  most  favorable  conditions  ;  and  there  is  fori  led 
what  might  be  called  the  parent  tidal  wave,  which,  entering  the  In- 
dian and  Atlantic  Oceans,  seems  to  control  their  tides. 

The  Map  of  Co-tidal  Lines,  or  simultaneous  tides,  on  page  63,  shows  the  succes- 
sive positions  and  directions  of  the  crest  of  the  tidal  wave,  at  intervals  of  one 

hour.  Each  line  passes  through 
places  having  high  water  at  the  same 
hour,  the  hours  being  marked  on  the 
lines  in  Roman  numerals.  The  more 
rapidly  and  regularly  the  wave  ad- 
vances, the  further  apart  and  more 
nearly  parallel  are  the  co-tidal  lines 
which  exhibit  its  position  at  sueces- 
spring  tides.  sive  hours. 

2.  Tidal  Wave  of  the  Pacific.     The  Parent  wave,  which 
originates  in  the  central  and  southern  Pacific,  moves  on  most  swiftly 
in  the  broad,  deep,  and  unobstructed  basin  lying  south  of  the  Tropic  ' 
of  Capricorn.     There,  also,  it  preserves  its  normal  direction  west- 
ward, and  its  crest  extends  nearly  north  and  south. 

In  the  equatorial  Pacific  its  progress  is  obstructed  by  the  nume-  ' 
rous  oceanic  islands  ;  and,  reaching  the  shallow  seas  of  the  great 
Indian  Archipelago  (see  page  60,  Topic  III.),  it  becomes  exceedingly  j 
slow  and  irregular.     (See  Map  of  Co-tidal  Lines.~) 

In  the  northeastern  portion  of  this  basin,  the  tidal  wave  is  deflectec 

northward  and  eastward.     The  deflected 
wave  strikes   the    American   shores,    be-l 
tween  California  and  Alaska,  at  the  same 
hours  at  which  the  direct  wave  strikes  the 
Asiatic  shores,  between  Kamchatka  and 
Japan.     A  reflected  wave  also   starts  in 
the   longitude  of  the  Galapagos  Islands ; ' 
and,  advancing  eastward  and  southward] 
along  the  South  American  coasts,  it  meetsl 
the  tide  wave  from  the  south  Atlantic  at] 
Cape  Horn. 


NEAP  TIDE 


! 


NEAP   TIDES. 


QUESTIONS   ON   THE   MAP   OF  -CO-TIDAL 

LINES. 

Note.  —  The  co-tidal  lines  are  numbered  from  I.  to  XII.  in  J 
elusive,  corresponding  with  the  divisions  of  the  dial.    By  observ- 
ing the  numbers  on- the  lines,  at  given  places,  one  learns  the  n  um- 
ber of  hours  required  for  the  wave  to  pass  from  the  one  to  the 
other.     For  example,  the  line  at  the  Sandwich  Islands  is  num-  t 
bered  II.,  while  that  at  Sitka, on  the  American  coast,  is  X.    This 
6hows  that  the  latter  place  has  high  tide  eight  houn  later  than  I 
the  former. 

What  part  of  the  North  American  coast  has  high  water  at  the  same  hour  with  the  Sandwich 
Islands  ?     How  many  hours  between  high  water  at  the  Sandwich  Islands  and  at  New  Zealand?! 
(See  note  above.)    How  much  of  the  American  coast  has  high  water  at  (he  same  hour  with! 
San  Francisco  ? 

How  long  is  the  tidal  wave  in  passing  from  the  southern  point  of  Kamchatka  to  the  souther 
point  of  the  Japan   Islands?     How  long  is  the  tidal  wave  in  passing  from  the  Galapagos 
Islands,  across  the  Pacific,  to  Kamchatka  and  New  Zealand  ? 

How  long  from  the  Galapagos  Islands  to  the  southern  extremity  of  South  America?  Hovrj 
long  from  the  Sandwich  Islands  northward  to  the  southern  coast  of  Alaska  ? 

In  what  direction  does  the  tidal  wave  advance  through  the  middle  and  northern  part  on 
the  Atlantic  Ocean?     What  places  have  high  tide  at  the  same  hour  with  Rio  Janeiro? 

How  long  is  the  tidal  wave  in  passing  from  Rio  Janeiro  to  Cape  Race  ? 

What  portions  of  the  North  American  coast  have  high  tide  at  the  same  hour  with  Newl 
York? 

How  long  is  the  tidal  wave  in  passing  from  New  Zealand,  through  the  Indian  and  Atlantic! 
Oceans,  to  Iceland?     How  long  in  passing  from  New  Zealand  to  Muscat,  in  Arabia? 

What  direction  does  the  tidal  wave  take  in  the  eastern  half  of  the  Indian  Ocean? 


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WAVES  AND  TIDES. 


3.  Tides  of  the  Indian  and  Atlantic  Oceans.  The  tides 
of  the  Indian  and  Atlantic  Oceans  seem  to  be  either  overpowered 
by,  or  merged  into,  the  great  wave  generated  in  the  south  Pacific. 

This  wave  advances  rapidly  through  the  deep  waters  of  these  ba- 
sins ;  but  it  is  greatly  retarded  in  the  northern  portions  of  the  In- 
dian Ocean.  Muscat,  near  the  northern  extremity  of  the  Arabian 
Sea,  has  high  water  at  the  same  hour  as  Rio  Janeiro  on  the  west- 
ern shores  of  the  Atlantic. 

In  the  middle  and  south  Atlantic  the  tide  wave  advances  north- 
westward ;  in  the  northern 
part  it  moves  towards  the 
northeast,  following,  in  both 
cases,  thj  direction  of  the 
narrow  ocean  basin. 

The  course  of  the  tidal  wave  on 
the  coast  of  the  British  Isles,  illus- 
trates forcibly  its  retardation  in 
shallow  and  narrow  arms  of  the  sea. 

The  main  wave  of  the  north  At- 
lantic advances  from  Brest,  on  the 
western  coast  of  France,  to  Ber- 
gen, on  the  coast  of  Norway,  in 
four  hours.  The  branch  entering 
the  English  Channel  has,  during 
the  same  time,  only  reached  South- 
ampton, and  that  in  the  Irish  Sea 
has  arrived  at  Dublin. 

The  main  wave,  entering  the 
North  Sea  from  the  north,  descends 
slowly  along  the  coasts  of  Scotland 
and  England ;  and  finally  meets  the 
branch  from  the  Channel,  which, 
having  passed  the  Strait  of  Dover, 
advances  along  the  coasts  of  Hol- 
land and  Germany.    (See  Fig.  30.) 


V.  Height  of  Tides. 

FIG.  30. 

1.  Variations  in  Level.  The  height  of  the  tide  depends. on 
local  circumstances.  In  the  midst  of  the  Pacific  it  is  scarcely  more 
than  two  feet,  which  may  be  considered  its  normal  level.  But  when 
dashing  against  the  land,  or  forced  into  deep  gulfs  and  estuaries,  the 
accumulating  tide  waters  sometimes  reach  a  great  height. 


On  the  eastern  coast  of  North  America,  the  average  rise  of  the  tido 
is  from  nine  to  twelve  feet.  At  the  entrance  to  the  Bay  of  Fundy, 
however,  it  rises  eighteen  feet,  while  at  the  head  of  that  bay  it  reached 
60,  and  in  the  highest  spring  tides,  even  70  feet.  At  Bristol,  in 
England,  the  spring  tides  rise  to  40  feet ;  and  at  St.  Malo,  on  the 
south  coast  of  the  English  Channel,  they  reach  50  feet. 

2.  Effects.  Differences  in  level,  produced  by  high  tides,  cause 
currents  which  vary  in  force  and  direction  with  the  condition  of  the 
tide,  producing,  in  some  cases,  dangerous  whirlpools.     The  famous 

Maelstrom,  off  the  coast  of 
Norway,  is  but  a  tidal  cur- 
rent, which  rushes  with  great 
violence  between  two  of  the 
Lofoden  Islands,  causing  a 
whirling  motion  in  the  water 
which  is  reversed  at  each  ebb 
and  flow  of  the  tide. 

Such  is,  also,  the  famous 
whirlpool  of  Charybdis,  in 
the  Strait  of  Messina,  and 
many  others  of  less  note. 
The  powerful  currents  of 
Hell  Crate,  in  the  passage 
from  Long  Island  Sound  to 
New  York  Bay,  are  due  to  a 
similar  cause,  high  water  oc- 
curring at  different  hours  in 
the  bay  and  in  the  west  end  . 
of  the  sound. 

1.  Bore.  In  estuaries  into  which 
great  rivers  flow,  the  resistance 
offered  by  the  current  of  the  stream 
to  the  entrance  of  the  tide,  produces 
a  huge  wave  called  the  Bore,  which, 
like  a  moving  wall  of  water,  advan- 
ces with  great  rapidity  and  a  deep 
roaring  noise  up  the  stream  to  the  limit  of  tide  water.  The  Hoogly,  a  mouth  of 
the  Ganges,  the  Tsien-tang  in  China,  and  the  Amazon,  afford  the  most  remark- 
able examples  of  this  phenomenon.  The  bore  of  the  Tsien-tang  rises  thirty  feet 
in  height,  and  travels  at  the  rate  of  twenty-five  miles  an  hour.  In  the  Amazon 
five  bores,  each  about  fifteen  feet  in  height,  may  sometimes  be  seen  rushing 
up  the  river  one  after  the  other  within  the  space  of  200  miles. 


CO-TIDAL    LINES    OF    liHITISH    ISLES 


ANALYSIS   OF   SECTION  IU. 


I. 

Oceanic  Movements. 

a.  Causes  of  movement  in  sea  water 

b.  Classes  of  movements. 

II. 

Waves. 

a.  Description  of  wave  movement. 

b.  Cause.    Variation  in  waves. 

c.  Advance  of  waves.    Swell. 

III. 

Tides. 

1. 

Phenomenon  Described. 

a.  Kind  of  motion. 

b.  Difference  between  tides  and  waves. 

c.  Periods  of  tide.     Flood.    Ebb.    High  water.    Low  water 

d.  Interval  between  two  consecutive  high  tides. 

e.  Hour  of  high  water  on  successive  days. 

2.  Mode  op  Production  of  Tides. 

a.  Comparative  influence  of  Moon  and  Sun. 

b.  Production  of  tidal  wave  under  Moon. 

c.  Production  of  tidal  wave  on  opposite  side  of  globe. 

d.  Areas  of  simultaneous  high  water. 

e.  Areas  of  simultaneous  low  water. 

f.  Advance  of  tidal  system  around  globe. 

3.  Spring  Tides  and  Neap  Tides. 

a.  Want  of  coincidence  in  lunar  and  solar  tides. 


b.  Spring  tides,  when  and  how  formed,  high  water,  low  water. 

c.  Neap  tides,  when,  how  formed,  high  water,  low  water. 

d.  Highest  spring  tides.     Lowest  ueap  tides. 

IV.  Course  of  Tidal  Wave. 

1.  Introduction. 

a.  Course  in  case  a  uniform  ocean  covered  the  globe. 

b.  Influence  of  continents  on  course. 

c.  Regularity  and  velocity  of  motion. 

d.  Explanation  of  map  of  co-tidal  lines. 

2.  Tidal  Wave  of  Pacific. 

a.  Course  of  parent  or  primary  tide  wave. 

b.  Tidal  wave  iu  equatorial  Pacific. 

3.  Tidal  Wave  op  Indian  and  Atlantic  Oceans. 

a.  Relation  to  Pacific  tide  wave. 

b.  Progress  in  deep  waters. 

c.  Retardation. 

d.  Course  around  British  Isles. 

V.  Height  of  Tide. 

1.  Variations  of  Level. 

a.  Height  depends  on  what. 

b.  Normal  level. 

c.  High  water  on  North  American  coast.    Exceptions. 

d.  Spring  tides  in  Bristol  and  English  Channel 

2.  Results  of  Differences  of  Level. 

3.  Bore  —  how  formed.    Examples. 


IV.  — MARINE   CURRENTS. 


I.  General  Circulation. 

1.  The  Ocean  Currents  are  vast  rivers  in  the  sea,  which  move 
on  steadily  through  water  comparatively  at  rest,  and  are  often  differ- 
ent from  the  latter  in  color  and  temperature.     Some  are  hundreds 

n  ilcs  broad,  thousands  of  feet  deep,  and  have  a  course  embrac- 
ing the  larger  part  of  the  ocean  in  which  they  move.  Currents  ex- 
ist not  only  at  the  surface  but  in  the  deep  waters,  where  their  course 
is  frequently  in  a  different  direction  from,  sometimes  even  opposite 
to,  that  of  the  surface  currents. 

2.  Equatorial  Currents.  Within  and  near  the  tropics  the 
waters,  under  the  influence  of  the  constant  trade  winds  (see  page 
77,  Topic  III.),  advance  westward  around  the  globe,  forming  a  vast 
Equatorial  Current,  50°  or  more  in  breadth. 

Reaching  the  eastern  shores  of  the  continents,  in  each  ocean,  this 
great  current  separates,  one  part  turning  northward  and  the  other 
southward.  Advancing  towards  the  poles  these  branches  swerve 
gradually  eastward ;  and,  reaching  the  middle  latitudes,  they  cross 
the  ocean,  striking  the  western  shores  of  the  continents.  Finally,  a 
part  at  least  of  the  water  returns  to  the  equatorial  regions,  while 
the  remainder  continues  its  course  towards  the  poles. 

Thus  is  formed,  on  each  side  of  the  equator,  a  vast  elliptical  circuit 
of  moving  waters,  occupying  the  entire  breadth  of  the  ocean  basins, 
and  extending  over  the  tropical  and  middle  latitudes.  In  the  centre 
is  a  broad  expanse  of  quiet  water,  which  is  covered,  to  a  large  ex- 
tent, with  sea  weed,  forming  the  so  called  Sargasso  Seas. 

The  main  causes  of  these  vast  movements  in  the  ocean  are  found  in 
the  winds,  the  excessive  evaporation  within  the  tropics  which  tends 
to  lower  the  level  of  the  water  there,  and  the  differing  temperatures 
of  polar  and  equatorial  regions.  The  cold  waters  of  the  higher  lat- 
itudes, being  heavier,  tend  constantly  to  flow  into  the  warmer  wa- 
ters of  the  equatorial  seas  ;  and  the  latter,  being  displaced  by  the  for- 
mer, flow  away  as  surface  currents  towards  the  poles. 

3.  Two  series  of  currents,  of  opposite  character,  pervade  the 
sea  iii  high  latitudes  ;  —  the  cold,  flowing  from  the  polar  regions  to- 
wan  Is  the  equatorial ;  and  the  warm,  flowing  in  the  opposite  direction. 
In  the  middle  latitudes,  where  the  opposing  currents  meet,  the 
cold,  being  heavier,  sink  beneath  the  warm  and  disappear,  continu- 
ing their  course  in  the  deep  waters.  These  under  currents,  having 
reached  the  inter-tropical  seas,  gradually  rise  again  to  the  surface, 
where  they  become  heated ;  and,  contributing  their  waters  to  the 
great  equatorial  current,  which  flows  westward  on  each  side  of  the 
equator,  they  finally  return  towards  the  poles. 

Hence  the  general  currents  of  the  sea  are  of  three  classes :  the 

olar,  the  Equatorial,  and  the  Return  Currents. 

3.  Direction.      The    Polar   and  Return  Currents,  were   they 

ted  upon  by  no  external  force,  would  move  in  the  line  of  the  me- 

•idians,  taking  the  shortest  course  between  the  poles  and  the  equator. 

Both  are,  however,  deflected  from  this  course  by  the  unceasing 

ion  of  the  Earth's  rotation,  —  the  Polar  Currents,  as  they  advance, 

mding  more  ai!#  more  towards  the  west,  and  the  Return  Currents 

wards  the  east  ;  and  their  directions  are  still  farther  modified  by 

;e  forms  of  the  basins  of  the  several  oceans,  and  the  influence  of  the 

'evading  winds  in  the  different  zones. 

Since  the  Earth  performs  one  entire  rotation  on  its  axis  every  twenty-four 
mrs,  the  velocity  of  rotation  at  the  equator,  must  be  somewhat  more  than  1000 
les  an  hour.  As  each  successive  parallel  has  a  less  circumference  than  the  pre- 
leding,  the  velocity  of  rotation  diminishes  with  increasing  latitude,  until  at  the 
poles  it  is  zero. 


If,  therefore,  particles  of  water,  or  of  air,  move  from  the  polar  regions  towards 
the  equator,  each  s>tep  in  advance  will  bring  them  upon  parallels  where  the  rota- 
tion is  more  and  more  rapid.  The  new  velocity  cannot  be  instantaneously  acquired, 
conseque^j^  at  each  successive  parallel,  the  moving  particles  are  left  a  little 
behind,  or  to  the  west  of  their  previous  position ;  and  when  they  reach  the  tropics 
they  are  many  degrees  west  of  the  meridians  upon  which  they  laft  the  polar  regions. 

A  similar  cause  operates  to  give  the  Return  Currents  their  eastward  tendency. 
The  particles  moving  towards  the  poles  find,  at  each  successive  parallel,  a  rotary 
velocity  less  than  at  the  preceding.  Not  acquiring  the  new  and  less  rapid  mo- 
tion instantaneously,  they  gain  a  little  at  each  parallel,  and  find  themselves  slightly 
in  advance,  or  to  the  east  of  their  former  position. 

This  deflection  from  a  direct  north  and  south  course,  which  appears  in  the  at- 
mospheric as  well  as  in  the  oceanic  currents  (see  page  76,  Topic  3),  is,  therefore, 
the  result  of  a  change  of  latitude  of  the  moving  particles.  Were  they  to  remain 
upon  any  given  parallel,  their  westward,  or  eastward,  motion  would  cease  ;  for  the 
solid  globe,  the  waters,  and  the  atmosphere,  all  rotate  together,  in  obedience  to 
the  same  laws. 

In  the  northern  hemisphere,  the  Polar  and  the  Return  Currents 
both  preserve  their  normal  course,  the  former  flowing  towards  the 
southwest,  the  latter  towards  the  northeast.  In  the  southern  hemi- 
sphere, the  westerly  winds  which  prevail  beyond  the  tropics  and 
sweep,  without  interruption,  over  the  broad  expanse  of  the  southern 
sea,  turn  the  Polar  Current  out  of  its  normal,  northwesterly,  course, 
directing  it  towards  the  northeast.     (See  map,  page  66.) 


II.  Currents  of  the  Pacific. 

1.  The  Great  Equatorial  Current  of  this  ocean  occupies 
the  entire  breadth  of  the  torrid  zone,  and  consists  of  two  parts,  a 
north  and  a  south  current,  which  are  separated  by  a  narrow  counter 
current,  moving  slowly  eastward,  in  the  immediate  vicinity  of  the 
equator.  Both  branches  begin  near  the  American  shores,  and  ad- 
vance westward  at  a  nearly  uniform  rate  of  two  or  three  miles  an  hour. 

The  South  Equatorial  Current,  starting  from  the  South  Ameri- 
can coast,  off  Pttnta  Parina,  moves  on  uninterruptedly  across  the 
eastern  half  of  the  ocean ;  but  it  is  broken  up  in  the  western  part, 
where  its  path  is  obstructed  by  innumerable  islands.  The  northern 
portions  are  lost  among  the  numerous  channels  of  the  Indian  Archi- 
pelago. The  southern  portions  turn  southward,  forming  the  New 
Zealand  and  Australian  Currents ;  and  finally,  meeting  the  Antarc- 
tic Current,  they  return  eastward  with  it. 

The  North  Equatorial  Current,  flowing  through  an  unobstructed 
basin,  advances  unbroken  to  the  Philippine  Islands  where  it  divides, 
the  southern  portion  entering  the  Indian  Archipelago. 

2.  Return  Current.  The  principal  part  of  the  North  Equa- 
torial Current  turns  northward,  forming  the  warm  and  powerful  Jap- 
anese Current,  called  by  the  natives  the  Kuro  Sivo,  or  Black  Water, 
on  account  of  its  dark  blue  color.  This  is  the  Return  Current  of 
the  north  Pacific,  analogous  to  the  Gulf  Stream  in  the  north  Atlan- 
tic. South  of  the  Aleutian  Islands  it  is  deflected  from  its  northward 
course  and  crosses  the  ocean.  Returning  along  the  American  shores 
to  the  Tropic  of  Cancer,  it  chiefly  reenters  the  North  Equatorial  Cur- 
rent. A  small  branch  of  the  Kuro  Sivo  continues  along  the  Asiatic 
coast  to  Behring  Strait. 

3.  Polar  Currents  are  nearly  wanting  in  the  north  Pacific,  for 
the  narrow  and  shallow  passage  of  Behring  Strait,  connecting  it 
with  the  Arctic  Ocean,  does  not  permit  the  free  egress  of  the  polar 
waters.  Yet  a  small  current,  in  each  direction,  passes  through  the 
strait,  the  warm  on  the  eastern  shore,  towards  the  north,  the  cold 
on  the  western,  towards  the  south. 

In  the  south  Pacific,  on  the  contrary,  the  polar  waters  advance 
northward  in  the  form  of  the  broad  Antarctic  Drift  Current. 


MARINE  CURRENTS. 


120   Lougitude  West      SO     ft-om  Ore MKMiofa    40 


CURRENTS. 


Entered  "■— »i-rti,i</  to  Art  of  Conff'*^"'  in   thr  frar  lS?:i  bjt    ScrJbnet;  Arnurtrongi  To.   i>i  *A*-  (MIm  «/'  «A*  Librtu-ian  of  Cortprr-nr  ut  Wa.tfun^ton.  CT- 


QUESTIONS   ON  THE  MARINE  CURRENTS. 


I.  Pacific  Ocean. 

Where  does  the  South  Equatorial  Current  commence? 

In  what  longitude  does  it  first  divide  ? 

What  shores  are  bathed  by  the  southern  branches  of  this  current? 

What  islands  bathed  by  its  northern  branches? 

What  is  the  position  of  the  counter  current  in  regard  to  the  Equator? 

What  are  the  eastern  and  western  limits  of  this  current  ? 

In  what  longitude  does  the  North  Equatorial  Current  commence  ? 

How  does  this  current  compare  in  breadth  with  the  South  Equatorial  ? 

What  name  has  the  return  current -of  the  North  Pacific  in  the  western  half  of  its  course? 

Where  is  the  Kuro  Sivo  first  apparent? 

What  shores  are  bathed  by  this  current? 

Near  what  islands  does  the  Kuro  Sivo  divide  ? 

Whither  does  the  smaller  branch  go  ? 

What  name  is  given  to  the  greater  branch  of  the  Kuro  Sivo  ? 

Describe  the  course  of  the  North  Pacific  Current? 

What  seems  to  be  the  most  desirable  route  for  vessels  from  California  to  China? 

From  China  or  Japan  to  California?    Why  ? 

What  current  on  the  western  coasts  of  South  America  ? 

Whence  is  this  current  derived  ? 

Whither  does  it  go  ? 

What  is  the  direction  of  the  current  east  of  northern  Australia? 

What  is  the  direction  of  the  East  Australian  Current? 

Whence  are  these  two  currents  derived  ? 

What  is  the  direction  of  the  current  east  of  New  Zealand,  and  whither  does  it  go? 

Whence  come  the  currents  on  the  west  coast  of  North  America? 

Whence  are  all  the  currents  on  the  west  coast  of  South  America  derived? 

What  is  their  probable  effect  upon  the  climate?    Why? 

Name  the  principal  cold  current,  I  of  the  Pacific. 

The  warm  currents. 


I.  Atlantic  Ocean. 

Trace  the  water  of  this  ocean,  from  the  Cape  of  Good  Hope  to  North  Cape,  naming  the  cur- 
rents, and  the  coasts  and  islands  bathed  by  each. 


Trace,  in  like  manner,  the  currents  from  the  Cape  of  Good  Hope  to  Cape  Horn. 

Where  is  the  Gulf  Stream  first  apparent? 

Whither  does  this  current  go  ? 

What  current  bathes  the  southern  shores  of  Iceland  ? 

What  current  flows  between  Iceland  and  Greenland  ? 

What  is  the  position  of  the  North  Equatorial  Current  ? 

How  does  the  Equatorial  Counter  Current,  in  the  Atlantic,  compare  with  that  in  the  Pacific 
in  position  and  extent  ? 

Where  does  the  South  Equatorial  Current  originate  ? 

Whither  does  the  north  branch  of  this  current  go  ? 

Whither  does  the  south  branch  mainly  go  ? 

Whence  are  all  the  currents  on  the  eastern  and  northern  coasts  of  South  America  derived? 

How  does  their  influence  on  the  climate  of  the  coasts  differ  from  that  of  the  Peruvian 
Current?    Why? 

Whence  is  the  current  on  the  western  coast  of  south  Africa  derived  ? 

Whence  are  the  currents  on  the  western  coasts  of  north  Africa  and  Europe  ? 

What  is  their  probable  influence  on  the  climate  of  those  coasts?    Why? 

Whence  are  the  currents  on  the  larger  part  of  the  eastern  coast  of  North  America  ? 

How  do  the  currents  compare  in  direction  on  the  opposite  sides  of  the  north  Atlantic? 

What  is  the  direction  of  the  currents  at  the  west  of  Greenland  ? 

How  do  the  polar  currents  of  the  north  Atlantic  compare  in  extent  with  those  of  the  north 
Pacific? 

Why  is  this? 

Name  all  the  warm  currents  of  the  Atlantic. 

Name  the  cold  currents  of  the  Atlantic.  .^flfe. 


III.  Indian  Ocean. 

Trace  the  course  of  the  currents  from  the  Cape  of  Good  Hope  to  Australia,  and  return. 
Whence  is  the  South  Australian  Current  derived  ? 
What  current  flowing  between  India  and  Africa  ? 

What  is  the  direction  of  the  currents  in  the  northern  part  of  the  Indian  Ocpan?     (See 
page  67,  Topic  IV.) 
Which  are  the  warm  currents  of  this  ocean? 
To  what  part  of  the  Indian  Ocean  are  the  cold  currents  confined  ?     Why  ? 


MARINE   CURRENTS. 


67 


Bent  out  of  its  normal  course  by  the  strong  westerly  winds,  this 
polar  current  turns  eastward,  and  advances  to  the  South  American 
coast,  where  it  divides.  The  principal  branch  flows  northward,  un- 
der the  name  of  the  Peruvian  or  Humboldt  Current,  bathing  the 
coasts  of  Peru  with  its  cool  waters,  and  becoming  the  main  feeder  of 
the  South  Equatorial  Current.  The  smaller  branch,  turning  south- 
ward, rounds  Cape  Horn  and  enters  the  Atlantic. 

III.  Currents  of  the  Atlantic. 

1.  The  Equatorial  Current,  in  the  Atlantic,  owing  to  the 
narrowness  of  the  basin  and  the  projecting  angle  of  South  America, 
has  neither  the  extent  nor  the  regularity  it  shows  in  the  Pacific. 
The  northern  branch  is  less  marked,  and  the  counter  current  is  not 
well  defined  except  near  the  African  coasts. 

The  south  branch  advances  from  the  coast  of  Guinea  to  Cape  St. 
Roque,  the  eastern  point  of  South  America,  where  it  divides.  The 
smaller  division  forms  the  Brazilian  Current,  flowing  southward 
along  the  eastern  coast  of  South  America.  Finally  turning  to  the 
southeast,  under  the  name  of  the  Connecting  Current,  it  joins  the 
Antarctic  waters,  and  returns  with  them  to  the  Equatorial  Current. 

The  main  portion  of  the  south  current  continues  westward,  pass- 
ing the  mouth  of  the  Amazon  and  the  coast  of  Guiana ;  then,  uniting 
with  the  North  Equatorial  Current,  it  traverses  the  Caribbean  Sea 
and  the  Gulf  of  Mexico,  and  issues  into  the  north  Atlantic  basin  as 
the  Gulf  Stream. 

2.  The  Gulp  Stream,  which  first  becomes  apparent  near  the 
northeast  coast  of  Cuba,  advances  gently  eastward  to  the  Bahama 
Banks  ;  then,  turning  northward,  it  follows  the  American  coast,  with 
an  average  velocity  of  four  or  five  miles  an  hour,  gradually  expand- 
ing in  breadth  and  diminishing  in  depth. 

In  the  latitude  of  New  York  it  turns  eastward  and  crosses 
to  the  Azores,  where  it  divides.  The  main  branch,  bending  south- 
ward, enters  the  tropical  regions  off  the  coast  of  Africa,  and  returns 
to  the  North  Equatorial  Current.  The  northern  branch  continues 
its  northeast  course  to  the  British  Isles  and  Norway,  its  advance  in 
that  direction  being  favored  by  the  prevailing  southwest  winds. 

Near  its  origin  this  remarkable  current  has  a  breadth  of  32  miles,  and  a  depth 
of  more  than  2,000  feet ;  off  Cape  Hatteras  the  breadth  is  at  least  75  miles,  and 
the  depth  about  700  feet.  Its  temperature,  at  its  origin,  is  about  80°  Fahr. ;  and 
through  the  larger  part  of  its  course  it  is,  on  an  average,  from  10°  to  15°  Fahr., 
—  in  winter  from  20°  to  30°,  —  warmer  than  the  adjacent  waters.  Its  color  is  a 
deep  blue,  so  strongly  contrasting  with  the  greenish  color  of  the  sea  that  the  line 
of  contact  is  distinctly  traceable  by  the  eye.  Its  boundaries  are  sharply  denned, 
especially  on  the  west,  where  the  transition  is  immediate  from  the  cold  wall  of 
adjacent  waters  to  the  warm  waters  of  the  Gulf  Stream. 

In  the  middle  and  northern  part  of  its  course,  alternate  bands  of  cold  and  warm 
waters  occur.  This  is  due,  perhaps,  to  the  partial  mingling  of  colder  currents 
with 'the  warm,  or  simply  to  the  currents  of  warm  water  moving  into  the  quiet 
colder  waters  of  the  sea. 

The  comparatively  high  temperature  and  rapid  motion,  and  the  deep  blue  color 
of  the  Gulf  Stream,  distinguish  it  from  other  portions  of  the  ocean.  It  was  long 
supposed  to  be  a  phenomenon  of  an  exceptional  character,  to  account  for  which 
the  most  extravagant  hypotheses  were  invented.  A  better  knowledge  of  the  ocean 
currents,  ho\M||r,  shows  it  to  be  simply  a  Return  Current  like  the  Japanese,  the 
normal  charfl^H  which  is  intensified  by  the  peculiarities  of  the  Atlantic  basin. 

This  basin  nWscarcely  half  the  breadth  of  the  Pacific  basin ;  hence  the  Gulf 
Stream  retains,  throughout  its  course,  its  original  temperature  in  a  much  higher 
degree  than  the  Kuro  Sivo.  Again,  the  open  communication  of  the  Atlantic  basin 
with  the  Arctic,  giving  free  entrance  to  the  polar  waters,  while  the  north  Pacific 
is  closed  against  them,  causes  a  much  greater  contrast  between  the  Gulf  Stream 
and  the  surrounding  sea  than  is  presented  by  the  Japanese  Current. 

The  intermingling  of  the  warm  moist  air,  over  the  Gulf  Stream,  with  the  colder 
air  over  the  surrounding  sea,  causes  those  frequent  and  violent  storms  which  mark 
the  course  of  this  current  across  the  Atlantic. 


The  Gulf  Stream  transports  not  only  the  warm  waters  of  the  tropics,  but  car- 
ries with  it  large  quantities  of  drift  wood  from  the  tropical  forests.  This,  with 
debris  from  wrecked  vessels,  and  weed  from  the  vast  Sargasso  Sea,  it  throws  upon 
the  shores  and  islands  of  the  Arctic  regions  whither  it  flows,  the  drift  wood  form- 
ing a  valuable  gift  to  the  people  of  those  inhospitable  lands. 

3.  Two  main  Polar  Currents,  one  on  each  side  of  Greenland, 
uniting  off  Cape  Farewell,  carry  the  icy  waters  and  icebergs  of  the 
Arctic  to  the  American  shores,  as  the  Gulf  Stream  and  the  superin- 
cumbent air  transport  the  genial  temperature  of  more  southern  lati- 
tudes to  Europe.  In  the  latitude  of  Newfoundland  the  Polar  Cur- 
rent meets  the  Gulf  Stream,  and,  condensing  the  vapors  in  the  warm 
air  which  rests  upon  it,  produces  almost  constant  fogs.  Thence  as 
far  as  New  York,  the  polar  waters  flow  between  the  warmer  waters 
and  the  shore,  finally  disappearing  beneath  them. 

IV.  Currents  of  the  Indian  Ocean. 

The  North  Equatorial  Current,  in  this  basin,  is  overcome  by  the 
influence  of  the  Monsoons ;  and  it  flows  alternately  towards  and 
from  the  southwest,  its  principal  branch  being  known  as  the  Mala- 
bar current. 

The  South  Equatorial  Current  is  quite  regular,  extending  from 
Australia  to  Madagascar,  where  it  divides.  The  north  branch  forms 
the  warm  and  powerful  Mozambique  current,  west  of  Madagascar, 
and  near  the  southern  coast  of  Africa  it  is  joined  by  the  south 
branch.  South  of  the  Cape  of  Good  Hope  the  united  current  meets 
the  Antarctic  Drift  and  turns  backward  with  it  to  the  shores  of  Aus- 
tralia, where  it  reenters  the  equatorial  current. 


V.  Conclusion. 

Thus  is  kept  up,  in  each  of  the  three  great  ocean  basins,  a  con- 
stant circulation  of  the  marine  waters,  which  far  surpasses  in  mag- 
nitude the  greatest  circulatory  systems  of  the  continents,  and  pro- 
duces important  modifications  in  the  climate  of  the  adjacent  lands. 

The  north  polar  currents,  transporting  their  icy  waters  into  the 
middle  latitudes,  are,  by  the  influence  of  the  Earth's  rotation,  thrown 
upon  the  eastern  shores  of  the  continents,  reducing  their  tempera- 
ture below  that  belonging  to  the  latitudes. 

The  return  currents,  on  the  contrary,  carrying  the  warm  waters, 
and  accompanied  by  the  warm  air  of  the  tropical  regions,  strike  the 
western  shores  of  the  continents,  and  raise  their  temperature  above 
that  belonging  to  their  latitudes.  Thus  on  the  opposite  shores  of 
the  northern  continents,  there  are  great  contrasts  of  temperature  in 
the  same  latitude,  due  in  a  considerable  degree  to  marine  circulation. 

Again,  the  position  of  the  warm  waters  on  the  surface  of  the  sea, 
while  the  cold  are  beneath,  doubtless  augments,  to  an  appreciable 
degree,  the  warmth  of  the  entire  temperate  zone. 

ANALYSIS  OP  SECTION  ni. 

I.  General  Currents. 

1.  Ocean  Currents. 

a.  Definition. 

b.  Extent. 

o.  Position  relative  to  surface, 
d.  Cause. 
2  Shies  or  Currents. 

a.  Cold  currents. 

b.  Warm  currents. 

c.  Results  of  meeting  of  cold  and  warm  currents. 

d.  Under  current  in  equatorial  regions. 

e.  Classes  of  general  currents. 

3.  Directions  of  Polar  and  Return  Currents. 

a.  Direction  in  absence  of  modifying  influence. 


68 


MARINE  CURRENTS. 


b.  Influence  modifying  directions.     Results. 

c.  Explanation  of  direction  of  polar  currents. 

d.  Explanation  of  direction  of  return  currents. 

e.  Farther  modifications  of  course  of  currents. 

II.  Currents  of  Pacific  Ocean.  % 

1.  Equatorial  Currents. 

a.  Breadth.    Subdivisions.    Velocity. 
South  Equatorial  current. 
North  Equatorial  current. 

2.  Return  Currents. 

a.  How  formed- 

b.  Course. 

3.  Polar  Currents. 

a.  North  Polar  currents. 

b.  South  Polar  current.    Direction.    Course  of  branches. 

III.  Currents  of  the  Atlantic. 

1.  Equatorial  Currents. 

a.  Effect  of  narrowness  and  form  of  basin. 

b.  South  branch  and  subdivisions. 

2.  Gulp  Stream. 

a.  Where  first  apparent. 

b.  Course  and  velocity  at  first. 

c.  Subdivisions  and  their  courses. 

Characteristics  of  Gulf  Stream. 
Peculiarities  how  accounted  for. 

3.  Polar  Currents. 

a.  Position  and  character. 

b.  Effect  on  meeting  Gulf  Stream. 

c.  Latitude  of  disappearance. 

IV.  Currents  of  Indian  Ocean. 

a.  North  Equatorial  current. 

b.  South  Equatorial  current. 


V.  Conclusion. 


a.  Magnitude  of  marine  circulations. 

b.  Climatic  effect  of  Polar  currents.     Of  Return  currents. 

■  Resulting  contrasts  in  coasts. 


REVIEW  OF  PART  III. 

Introduction.  (Page  47.) 
Enumerate  the  topics  discussed  in  the  introductory  section. 
What  is  the  effect  of  reducing  the  temperature  of  water  ? 
What  importance  has  this  exception  to  a  general  law  of  nature  ? 
Whence  is  the  rain  water  which  falls  upon  the  continents,  and  what  becomes  of  it  V 

Continental  Waters.  I.  (48.) 

Explain  the  formation  of  intermittent  springs. 

Where  are  springs  most  numerous,  and  why  in  this  position  ? 

How  are  rivers  combined  into  systems  ? 

Upon  what  does  the  amount  of  water  transported  by  a  stream  depend  ? 

How  does  the  erosion  vary  in  different  parts  of  the  course  of  a  stream  ? 

(49.)  What  is  the  result  of  the  lateral  erosion  in  the  middle  course? 

Explain  the  sinuosity  of  the  course  of  streams  through  the  bottom  land. 

How  are  the  windings  changed  in  high  water  ? 

Give  examples  of  the  amount  of  materials  transported  by  streams. 

How  is  this  transportation  effected,  and  how  do  the  materials  vary  in  different  parts  of  the 
course  ? 

How  does  the  deposit  of  the  transported  materials  vary  ? 

(50.)  Describe  the  formation  of  deltas. 

What  peculiarity  of  slope  do  deltas  show,  how  is  this  occasioned,  and  what  is  the  result 
of  it? 

In  what  part  of  the  course  of  a  stream  are  the  highest  falls  ?     Why  V 

Enumerate  the  topics  discussed  in  Section  I.,  with  their  primary  divisions. 

II.  (51.) 
What  peculiarities  of  form  distinguish  mountain  lakes  ? 
What  are  the  characteristics  of  lakes  in  plateaus  and  plains  ? 
How  is  the  formation  of  salt  lakes  to  be  accounted  for  ? 
Upon  what  does  their  size  depend  ?    Examples. 

(52.)  In  what  continents  are  lakes  most  numerous?    Character  of  the  lakes  in  each? 
Enumerate  the  topics  and  sub-topics  discussed  in  Section  II. 

III. 

What  is  the  influence  of  the  characteristic  structure  of  North  America  upon  its  drainage  ? 

What  is  the  main  water-shed,  and  what  great  streams  flow  from  it  ? 

(53.)  Describe  the  formation  of  the  Mississippi  basin. 

What  is  the  position  of  its  three  principal  affluents,  and  what  determines  this  position? 

How  do  the  eastern  affluents  compare  with  the  western  in  the  amount  of  water  transported  ? 

Why  this  difference  ? 

What  especially  characterizes  the  St.  Lawrence  basin? 

Name  the  other  river  systems,  and  the  groups  of  smaller  streams,  in  North  America. 

(54.)  How  do  the  systems  of  the  central  plain  compare  with  the  others?    Why  is  this? 

Enumerate  the  topics  discussed  in  Section  III. 


IV. 

How  does  the  general  plan  of  drainage  in  South  America  compire  with  that  in  North 
America  ? 

What  is  the  effect  of  the  inequality  of  the  continental  slopes  ? 

How  is  the  absence  of  lakes  in  South  America  to  be  explained  ? 

What  is  the  structure  of  the  Amazon  basin,  and  the  main  source  of  its  waters? 

How  does  the  Amazon  compare  with  other  streams  in  its  volume  of  water?    Why? 

Name  the  remaining  systems  of  South  America,  and  the  corresponding  streams  of  ^cnh 
America. 

(55.)  Enumerate  the  topics  discussed  in  Section  IV.,  and  their  primary  divisions. 


Describe  the  general  plan  of  drainage  in  eastern  Asia. 

Why  is  it  so  different  from  the  plan  of  the  American  continents? 

Enumerate  the  principal  streams  on  each  slope. 

Describe  the  drainage  of  western  Asia. 

What  are  the  hydrographical  centres  of  Europe? 

Describe  the  drainage  of  High  Europe. 

What  governs  the  direction  of  the  flowing  waters  of  a  continent? 

(56.)  How  does  the  course  of  the  streams  of  High  Europe  illustrate  this  fact? 

Describe  the  drainage  of  Low  Europe. 

How  do  its  streams  compare  with  those  of  High  Europe  ? 

Enumerate  the  topics  discussed  in  Section  V.,  with  their  several  subdivisions. 

VI.  (57.) 
What  is  the  general  plan  of  drainage  in  Africa  ? 
Describe  the  course  of  the  Nile,  its  valley,  and  its  inundations. 
Describe  the  other  river  systems  of  Africa. 

From  what  part  of  the  continent  do  these  systems  derive  their  waters? 
What  peculiarity  in  regard  to  rivers  is  exhibited  by  Australia? 
Upon  what  does  the  plan  of  drainage  in  each  continent  depend  ? 
What  oceans  receive  the  larger  part  of  the  flowing  waters  of  the  globe  ? 
What  is  the  reason  of  this  ? 
Enumerate  the  topics  discussed  in  Section  VI.,  with  their  subdivisions. 

The  Sea.  I.  (58.) 
What  is  the  composition  of  sea  water? 
How  does  the  temperature  of  the  surface  vary  ? 
What  is  the  temperature  of  the  deep  waters  ? 
Describe  the  bottom  of  the  sea. 
Enumerate  the  topics  discussed  in  Section  I.,  with  their  se*ral  subdivisions. 

II.  (59.) 
Describe  the  forms  of  the  several  ocean  basins. 

How  are  coast  waters  classified,  and  what  class  characterizes  each  ocean? 
How  do  the  oceans  compare  in  regard  to  islands? 
Describe  the  bed  of  the  Atlantic  Ocean. 

(60.)  How  does  the  bed  of  the  oceans  differ  from  the  surface  of  the  continents? 
Describe  the  bed  of  the  Indian  Ocean. 
What  is  the  estimated  depth  of  the  Pacific? 

How  do  inland  and  border  seas  compare  with  the  oceans  in  depth  ?     Examples. 
What  is  probably  the  greatest  depth  of  the  sea  ? 
(61.)  Enumerate  the  topics  discussed  in  Section  II.,  with  their  several  divisions. 

III. 

What  are  the  different  classes  of  movement  in  the  waters  of  the  sea  ? 
Describe  the  wave  movement,  and  the  advance  of  the  wave. 

Describe  the  tides,  their  cause,  the  extent  of  the  movement,  and  the  several  periods  of  the 
tides. 
How  are  the  tidal  waves  produced  on  opposite  sides  of  the  globe  ? 
(62.)  Explain  the  spring  tides  and  the  neap  tides. 

Upon  what  does  the  velocity  of  the  movement  of  the  tidal  wave  depend  ? 
Describe  the  tidal  wave  of  the  Pacific. 

Why  is  the  progress  of  the  wave  more  rapid  in  mid-ocean  than  along  the  coasts? 
(63.)  What  is  the  normal  height  of  the  tide  wave? 
Why  is  it  higher  along  the  coasts  and  in  estuaries? 
Enumerate  the  topics  discussed  in  Section  III.,  with  their  several  divisions. 

IV.  (65.) 

Describe  the  general  circulation  of  the  oceanic  waters. 

What  are  the  three  classes  of  ocean  currents  ? 

What  is  the  normal  direction  of  the  polar,  and  of  the  return  currents  ?^| 

How  is  this  direction  caused  ? 

How  do  the  polar  currents  of  the  southern  hemisphere  vary  from  this  direction? 

Describe  the  equatorial  current  of  the  Pacific. 

Describe  the  course  of  the  Kuro  Sivo. 

(67.)  Describe  the  equatorial  current  of  the  Atlantic. 

Describe  the  Gulf  Stream,  its  course,  velocity,  and  temperature. 

How  and  why  does  it  differ  from  the  Kuro  Sivo? 

What  is  the  climatic  influence  of  the  ocean  currents? 

What  is  the  effect  of  the  expansion  of  the  warm  currents  on  the  surface  of  the  sea,  whii,, 
the  cold  are  beneath  ? 


PART    IV 


THE    ATMOSPHERE. 


I.  —  INTRODUCTION. 

I.  Tlif  Atmosphere  a  Geographical  Element. 

1.  Its  Relation  to  the  other  Elements.  The  Atmosphere, 
that  vast  ocean  of  air  at  the  bottom  of  which  we  live,  forms  the 
third  great  geographical  element  of  the  Earth.  Enveloping  both 
the  land  and  the  water,  it  absorbs  the  heat  and  vapors  caused  by 
the  action  of  the  sun  upon  the  surface  of  both  ;  and,  through  the 
medium   of  the 

winds,  carries  invis- 
ible moisture  and 
fertilizing  rains 
from  the  sea  to  the 
parched  lands. 

2.  Composition. 
The  atmosphere  is 
a  mechanical  mix- 
ture of  oxygen  and 
nitrogen,  in  the  pro- 
portion, by  volume, 
of  21  parts  of  the 
former  to  79  of  the 
latter  ;  with  a  very 
small  quantity  of 
carbonic  acid,  and 
more  or  less  of  wa- 
tery vapor  held  in 
suspension.  It  is 
among  the  most 
elastic  bodies  in  na- 
ture, expanding  or 
contracting  with 
the  slightest  in- 
crease or  diminu- 
tion of  temperature,  or  variation  in  the  pressure  which  it  supports. 

3.  Weight  and  Pressure.  The  weight  of  the  atmosphere  is 
measured  by  its  pressure  on  the  barometer.1  This  instrument  is  a 
slender  glass  tube  about  a  yard  in  length,  closed  at  one  end,  then 
filled  with  mercury  and  reversed,  the  open  end  being  placed  in  a 
cup  of  the  same  fluid. 

The  atmosphere,  pressing  upon  the  fluid  in  the  cup,  keeps  within 
the  tube  a  column  of  mercury  exactly  sufficient  to  balance  its  own 
weight.     At  the  level  of  the  sea  this  column,  measured  by  a  scale 

1  From  the  Greek  baros,  weight,  and  metron,  measure. 


..   \I:-.     I  .i    I  :!iir;i-ii-.     <  1..   I  ':..::.'■■  ■../  ..      Iih.  Dhawalagii  i.      1-   Kvcrcst.      Or.   OntV'l 

Lebanon  Mts.    M.  B.  Mont  Biiuic.    Po.  Popocatepetl.    By.  Pyrenees.    Sa.  Soratu.  'Si 

W.  Mt.  Washington.     Observers:  G.  Gerard.    G.  L.  Gay  Lussac.    Gi.  Glaisher. 


FIG  31.      DENSITY    AND    PHESSUHE   OF   THE   AIK   AT   DIFFERENT   ALTITUDES. 


attached  to  the  instrument,  is  about  thirty  inches  in  height.  The 
weight  of  the  entire  atmosphere,  therefore,  is  equivalent  to  that  of  a 
layer  of  mercury  thirty  inches  deep,  covering  the  globe,  and  exert- 
ing a  pressure  of  fifteen  pounds  on  every  square  inch  of  its  surface. 

When,  from  any  cause,  the  pressure  of  the  air  increases,  the  ba- 
rometer rises  ,  when  it  decreases  the  barometer  falls. 

4.  Density.  The  air,  being  a  highly  elastic  body,  the  lower 
layers,  which  support  the  pressure  of  the  entire  atmosphere,  are  the 
most  dense  ;  and  the  density  diminishes  upward  with  the  decrease  of 

pressure  and  the 
consequent  increase 
of  volume. 

The  law  of  varia- 
tion is  exhibited  in 
the  table  below,  in 
which  the  volume 
and  density  of  a 
given  weight  of  air 
at  the  sea  level,  un- 
der a  barometric 
pressure  of  thirty 
inches,  is  taken  as 
unity. 

It  will  be   seen 
that  one  half  of  the 
entire    atmosphere, 
by  weight,  is  con- 
densed   within    3$ 
miles  —  about   18,- 
000  feet  — of  the 
sea  level ;  and  fully 
two  thirds  are  be- 
low the  level  of  the 
summit    of    the 
highest   mountains. 
This   fact    has   an    important 
bearing,  both  on  the  influence 
of    mountains   in  directing  or 
modifying    the  course    of    the 
winds,  and  on  the  general  cli- 
matic phenomena  of  the  globe. 

Figure  31  shows  the  diminution  of 
barometric  pressure,  with  increasing 
altitude,   up   to   the    highest   points 
reached   by   observers,   either   upon 
mountains  or  by  balloon,  the  highest  being  Glaisher's  balloon  ascent  to  36,670  feet. 


I'k.    Hi.  Hindoo  Koosh.     K.  Kilinwi  Njaro. 
Scandinavian  Mts.    T.  Torrcy's  Pk. 
Gu.  Green.    II.  Humboldt. 


Height  of 

Barometer. 

Inches. 

Volume  of 
a  given 
weight. 

Density. 

Miles  above 
sea  level. 

30.00 

1 

1        ' 

0 

15.00 

2 

\ 

3.4 

7.50 

4 

\ 

6.8 

.3.75 

8 

\ 

10.2 

1.81 

16 

A 

18.6 

.93 

32 

A 

17.0 

70 


ASTRONOMICAL   CLIMATE. 


5.  Height  of  the  Atmosphere.  In  consequence  of  the  above 
law  of  diminution,  it  is  calculated  that,  at  the  height  of  from  45  to 
50  miles  above  the  sea,  the  atmosphere  becomes  so  rarefied  that  the 
barometric  pressure  is  nearly  or  quite  insensible.  If  this  be  taken  as 
practically  its  upper  limit,  the  atmosphere  appears  as  a  thin  film, 
measuring  not  much  moi'e  than  the  hundredth  part  of  the  radius  of 
the  Earth. 

6.  Its  Relation  to  Organic  Life.  In  the  atmosphere  alone 
the  highest  forms  of  vegetable  and  animal  life,  including  man  him- 
self, find  the  proportion  of  heat,  of  oxygen,  and  of  watery  vapor  req- 
uisite for  their  vitality  and  development.  It  thus  performs  the  part 
of  universal  mediator,  not  only  between  land  and  sea,  but  also  be- 
tween organic  and  inorganic  nature. 


II.  Climate. 

1.  Definition.  The  physical  agencies  acting  through  the  at- 
mosphere upon  organic  life,  constitute  climate,  of  which  heat  and 
moisture  are  the  essential  elements,  the  winds  being  the  medium  of 
circulation.  Temperature,  however,  is  the  fundamental  phenomenon 
of  climate ;  for  the  winds  and  the  rains  result  from  differences  in 
the  temperature  of  the  air. 

2.  Astronomical  Climate.  The  fundamental  laws  which  gov- 
ern the  climatic  conditions  of  our  globe  are  the  result  of  astronomical 
causes,  namely  :  the  direct  action  of  the  Sun's  rays  upon  the  Earth's 
surface,  the  spherical  form  of  the  Earth,  and  the  daily  and  yearly 
motions  of  the  latter.  These  causes,  operating  constantly,  establish 
permanent  inequalities  of  temperature  and  rainfall  in  different  lati- 
tudes ;  and  periodical  variations,  in  the  same  latituda,  in  different 
parts  of  the  year. 

The  general  climatic  conditions  belonging  to  a  region,  and  de- 
pending upon  its  latitude,  constitute  its  astronomical  climate. 

3.  Physical  Climate.  The  climate  belonging  to  a  place,  by 
its  latitude,  is  usually  modified,  to  a  greater  or  less  extent,  by  sec- 
ondary physical  agencies,  —  among  which  are  the  general  atmos- 
pheric and  marine  currents,  the  differing  power  of  land  and  water  to 
absorb  and  radiate  heat,  and  the  altitude  of  the  surface. 

The  astronomical  climate  of  a  region  thus  modified,  is  its  real,  or 
physical  climate.  This  depends  not  only  upon  its  latitude,  but  also 
on  its  position  in  regard  to  the  oceans,  the  direction  of  its  prevailing 
winds,  and  its  elevation  above  the  level  of  the  sea. 


analysis  of  SECriON  I. 

I.  The  Atmosphere  a  Geographical  Element. 

1.  Its  Relation  to  other  Elements. 

2.  Its  Composition  and  Elasticity. 

3.  Its  Weight  and  Pressure. 

4.  Its  Density. 

5.  Its  Height. 

6.  Its  Relation  to  Organic  Liu. 


II.  Climate. 


1.  Definition. 

a.  Essential  elements. 

b.  Fundamental  phenomenon. 

2.  Astronomical  Climate. 

a.  General  climatic  conditions  — how  caused. 

b.  Results  of  operation  of  astronomical  causes. 

c.  Astronomical  climate  defined. 

d.  Astronomical  climate  depends  on  what. 
8.  Physical  Climate. 

a.  Subordinate  agencies  modifying  climate 

b    Physical  climate  defined. 

c.  Physical  climate  depends  on  what. 


"  II.  —  ASTRONOMICAL   CLIMATE. 

I.  Distribution  of  Temperature. 

1.  General  Law.  The  amount  of  heat  produced  by  the  snn 
upon  the  Earth's  surf  ace,  is  greatest  near  the  Equator,  and  diminishes 
gradually  towards  the  Poles. 

2.  Causes  of  Variation.     Three  general  causes,  each  referable 
to  the  spherical  form  of  the  Earth,  combine  to  produce  the  gradua 
diminution  of  temperature  from  the  Equator  to  the  Poles. 

(1.)  The  angle  at  which  the  Sun's  rays  impinge  upon  the  surface 
In  the  Equatorial  regions  they  are  perpendicular  to  the  surface  o 
the  sphere,  and  there  produce  their  maximum  effect ;  but,  on  ac- 
count of  the  curved  outline  of  the  globe,  they  fall  more  and  more 
obliquely  with  increasing  latitude,  and  the  intensity  of  action  dimin- 
ishes proportionately.  At  the  Poles,  they  are  tangent  to  the  sur- 
face, and  their  effect  is  zero. 

(2.)  The  area  on  which  a  given  amount  of  heating  power  is  ex- 
pended, is  least  at  the  Equator,  consequently  the  resulting  heat  is 
greatest.      The  area  covered   increases,  and  the  effect  diminishes 
with  the  increasing  obliquity  of  the  Sun's  rays  in  higher  latitudes 
which,  as  we  have  seen  above,  results  from  the  spherical  form  of  the 
Earth. 

(3.)  The  absorption  of  heat  by  the  atmosphere,  as  the  Sun's  rays 
pass  through  it,  is  least  where  they  fall  perpendicularly,  —  that  is,  in 
the  Equatorial  regions,  —  and  increases,  with  their  increasing  obliq- 
uity, towards  the  Poles. 


II.  Influence  of  the  Earth's  Motions. 

1.  Motions  of  the  Earth.  The  Earth  revolves  constantly 
around  the  Sun,  and  at  the  same  time  rotates  upon  an  axis  inclined 
23  \°  towards  the  plane  of  its  orbit.  In  consequence  of  the  inclina- 
tion of  the  axis,  the  declination  of  the  Sun,  or  its  angular  distance 
from  the  Equator,  varies  with  the  advance  of  the  Earth  in  its  orbit, 
causing  periodical  variations  in  the  length  of  day  and  night  and, 
consequently,  in  temperature. 

2.  Positions  of  the  Vertical  Sun.  Vernal  Equinox.  On 
the  20th  of  March,  at  mid-day,  the  Sun  is  vertical  at  the  Equator. 
Rising  directly  in  the  east  it  ascends  the  heavens  to  the  zenith,  and, 
descending,  sets  directly  in  the  west. 

The  illuminated  hemisphere  extends  from  pole  to  pole,  and  em- 
braces half  of  every  parallel  of  latitude  ;  hence  every  point  on  the 
Earth's  surface  is  under  the  rays  of  the  Sun  during  half  of  the  diur- 
nal rotation  ;  the  days  and  nights  are  equal  all  over  the  globe  ;  and 
the  heating  power  of  the  Sun  is  the  same  in  both  the  northern  and 
the  southern  hemisphere.  (See  illustration  Orbit  of  the  Earth, 
page  5.) 

Summer  Solstice.  As  the  Earth  advances  in  its  orbit  the  vertical 
Sun  declines  northward  ;  and  on  the  21st  of  June,  at  the  Summer 
Solstice,  it  is  over  the  northern  Tropic,  23£°  from  the  Equator. 

The  illuminated  hemisphere,  extending  90°  on  each  side  of  the 
parallel  of  the  vertical  Sun,  reaches  23£°  beyond  the  north  pole  ;  but, 
at  the  south,  it  barely  touches  the  Antarctic  circle.  It  embraces  more 
than  half  of  each  parallel  north  of  the  Equator,  hence  throughout 
the  northern  hemisphere  the  day  is  longer  than  the  night,  the  differ- 
ence in  their  duration  increasing  with  the  latitude ;  and  all  points 
within  the  Arctic  circle  are  in  the  light  during  the  entire  rotation. 

In  the  southern  hemisphere,  less  than  half  of  each  parallel  being 
illuminated,  the  night  is  longer  than  the  day,  and  within  the  Ant- 


PHYSICAL   CLIMATE. 


71 


arctic  circle  there  is  constant  night.  The  heating  power  of  the  Sun 
is  now  at  the  maximum  in  the  northern  hemisphere,  while  in  the 
southern  it  is  at  the  minimum. 

At  the  Autumnal  Equinox,  on  the  23d  of  September,  the  distri- 
bution of  light  and  heat  upon  the  two  hemispheres  is  the  same  as  at 
the  Vernal  ;  and  at  the  Winter  Solstice,  on  the  22d  of  December,  it 
is  the  reverse  of  that  at  the  Summer  Solstice. 

3.  Variations  in  Temperature.  The  inequality  in  the  length 
of  the  days  in  different  parts  of  the  year,  occasioned  by  the  inclina- 
tion of  the  Earth's  axis,  is  of  itself  sufficient  to  produce  a  marked 
variation  in  temperature. 

During  the  day  the  Earth  receives  from  the  Sun  more  heat  than 
it  radiates  into  space  ;  while  during  the  night  it  radiates  more  than 
it  receives.  Hence  a  succession  of  long  days  and  short  nights  re- 
sults in  an  accumulation  of  heat,  raising  the  average  temperature 
and  producing  summer ;  while  long  nights  and  short  days  result  in  a 
temperature  below  the  average,  producing  winter. 

Again,  the  heating  power  of  the  Sun  in  each  hemisphere  is  greatest 
at  the  period  of  the  longest  days,  because  of  its  greater  altitude  in  the 
heavens ;  and  least  at  the  period  of  shortest  days.  Thus  long  days 
and  a  high  sun  operate  together  to  produce  the  high  temperature  of 
rammer ;  while  long  nights  and  a  low  sun  cause  the  low  temperature 
of  winter. 

4.  Varying  Inequality  of  Day  and  Night.  Law  of  varia- 
tion. The  inequality  of  day  and  night  increases  slowly  in  the  trop- 
ical regions,  but  more  and  more  rapidly  towards  the  polar  circles. 
Beyond  these  circles  the  Sun,  in  the  hemisphere  in  which  it  is  verti- 
cal, makes  the  entire  circuit  of  the  heavens,  without  sinking  below 
the  horizon,  for  a  period  varying  from  twenty-four  hours  to  six 
months  ;  while  in  the  opposite  hemisphere  there  is  a  corresponding 
period  of  continuous  night. 

The  following  table  gives  the  length  of  the  longest  day,  excluding  the  time  of 
twilight,  and  of  the  shortest  night,  in  the  different  latitudes,  with  the  difference  of 
duration  in  hours  and  minutes,  thus  exhibiting  more  clearly  the  above  law. 


Latitude. 

Longest 
Day. 

Shortest 
Night. 

Difference. 

Latitude. 

Longest 
Day. 

Shortest 
Night. 

Difference. 

Equator 

12.0  hours. 

12.0  hours. 

00.0  hours. 

55° 

17.3  hours. 

6.7  hours. 

10  6  hours. 

10° 

12.7      " 

11.3      " 

1.4      " 

60° 

18.7      " 

5.3      ■ 

13.4      " 

20° 

13  3      " 

10.7      " 

2.6      " 

Polar  Circles 

24.0      " 

0.0      " 

24.0      " 

Tropica 

13.5      " 

10.5      " 

3.0      " 

67J° 

1  month. 

0.0      " 

30° 

14.0      " 

10.0      " 

4.0      " 

69J° 

2  months. 

0.0      " 

36° 

14.5      " 

9.5      " 

5.0      " 

73.3° 

3 

0.0      " 

40° 

15.0      " 

9.0      " 

6.0      « 

78.3° 

4        " 

0.0      " 

45° 

15.6      " 

8.4      " 

7.2      " 

84° 

5       " 

0.0      " 

60" 

16.3      " 

7.7      " 

8.6      " 

North  Pole 

6       " 

0.0      " 

Result  of  Varying  Inequality.  In  the  tropical  regions,  where  the 
days  and  nights  vary  little  in  length,  the  temperature  is  nearly  uni- 
form throughout  the  year  ;  while  the  increasing  inequality  of  day 
and  night  towards  the  Poles,  causes  an  increasing  difference  between 
the  summer  and  the  winter  temperature. 

Again,  the  length  of  the  day,  in  the  summer  of  high  latitudes, 
compensates  for  the  diminished  intensity  of  the  Sun's  influence ;  so 
that  the  temperature,  in  the  hottest  part  of  the  day,  may  equal,  or 
even  exceed,  that  within  the  tropics.  A  summer  day  in  Labrador 
or  St.  Petersburg  may  be  as  warm  as  one  under  the  Equator  ;  but  in 
the  former  latitudes  there  are  only  a  few  days  of  extreme  heat  in  the 
year,  while  with  increasing  nearness  to  the  Equator  the  number  of 
warm  days  constantly  increases. 

5.  Seasons  in  Different  Latitudes.  The  high  latitudes  have 
short,  hot  summers,  and  long,  severe  winters.     The  transition  sea- 


sons, spring  and  autumn,  on  account  of  the  very  rapid  change  in 
the  length  of  the  days,  are  short  and  scarcely  perceptible. 

In  the  middle  latitudes  the  summer  and  winter  are  more  nearly 
equal  in  length,  with  less  difference  in  the  extreme  temperatures  ; 
and  the  transition  seasons  are  distinctly  marked.  Farther  towards 
the  Equator  the  summer  increases  in  length,  and  the  winter  dimin- 
ishes, while  the  tropical  latitudes  have  constant  summer. 

Though  in  middle  and  polar  latitudes,  the  intensity  of  the  Sun's 
rays  is  greatest  at  the  time  of  the  Summer  Solstice,  yet  the  highest 
degree  of  heat,  resulting  from  accumulation  during  the  long  days, 
does  not  occur  until  a  month  or  more  after  that  period.  The  lowest 
temperature,  consequent  upon  successive  losses  during  the  short 
days,  usually  occurs  a  month  or  more  after  the  Winter  Solstice. 

A  similar  fact  is  apparent  in  the  daily  alternations  of  temperature.  The 
highest  degree  of  heat  is  not  at  noon,  when  the  sun  is  highest,  but  about  two 
o'clock ;  and  the  lowest,  a  little  before  sunrise,  at  the  end  of  the  period  of  greatest 
radiation,  instead  of  at  midnight. 


ANALYSIS   OF   SECTION   IT. 

I.  Distribution  of  Heat  on  Globe. 

a.  General  law. 

b.  Causes  of  unequal  distribution. 

c.  Operation  of  each. 

II.  Effects  of  Earth's  Motions. 

1.  Motions  of  the  Earth. 

a.  Result  of  inclination  of  axis. 
2   Positions  of  Vertical  Sun. 

a.  Vernal  equinox. 

When  occurring.     Daily  course  of  Sun. 
Position  of  illuminated  hemisphere. 
Length  of  day  and  night. 
Comparative  heat  of  hemispheres. 

b.  Summer  solstice. 

When  occurring. 

Position  of  illuminated  hemisphere. 
Day  and  night  in  northern  hemisphere. 
Day  and  night  in  southern  hemisphere. 
Comparative  heating  of  hemispheres. 

c.  Autumnal  equinox  and  winter  solstice. 
S.  Variations  of  Temperature. 

a.  Variation  in  length  of  day. 

Effect  of  long  days  and  short  nights. 
Effect  of  long  nights  and  short  days. 

b.  Variation  in  heating  power  of  sun. 
4.  Varying  Inequality  op  Day  and  Night. 

a.  Law  of  variation. 

b.  Result  of  variation. 

Summer  day  of  high  latitudes. 


5.  Seasons. 


In  high  latitudes. 
In  middle  latitudes. 
In  tropical  latitudes. 

Time  of  highest  and  of  lowest  temperature- 
Daily  alternations  of  temperature. 


III.  PHYSICAL  CLIMATE. 


I.  Contrasts  in  the  same  Latitude. 

1.  Contrasts  Observed.  According  to  the  laws  of  astro- 
nomical climate,  all  places  having  the  same  latitude  would  have  the 
same  average  annual  temperature,  and  the  same  periodical  changes. 
Thermometric  observations,  however,  show  quite  a  different  state  of 
things.  In  many  cases  the  differences  in  average  annual  tempera- 
ture, in  regions  having  the  same  latitude,  and  the  resulting  contrasts 
in  the  aspects  of  nature,  are  extreme ;  while  the  differences  in  the 
character  of  the  seasons  are  no  less  strongly  marked. 

For  example;  — on  the  western  shore  of  the  Atlantic  Ocean  is  Labrador,  fro/..,r 
and  treeless ;  while  opposite,  in  the  same  latitude,  are  the  British  Isles,  with  their 
mild  climate,  fertile  soil,  and  rich  verdure.  New  York,  with  a  long  icy  winter, 
is  in  the  same  latitude  with  Naples,  surrounded  by  orange  groves  and  evergreen 


72 


WINDS. 


vegetation.  Again,  San  Francisco,  with  mild  winters  and  cool  summers,  is  on  the 
same  parallel  with  Washington,  where  a  burning  sun  in  summer  is  succeeded  by 
winters  so  cold  as  often  to  cover  the  Potomac  with  a  thick  coat  of  ice ;  and  the 
fruitful  plains  of  southern  China  lie  side  by  side  with  the  frozen,  and  almost  unin- 
habitable, wastes  of  Thibet. 

2.  Isothekmal  lines.  In  order  to  illustrate  the  actual  distri- 
bution of  heat,  irrespective  of  latitude,  Humboldt  devised  a  series  of 
lines  known  as  isothermals,1  or  lines  of  equal  average  temperature, 
as  ascertained  by  thermometric  observations.  Each  line  connects 
places  having  the  same  mean  temperature,  either  of  the  year,  a 
season,  or  any  one  month.  The  annual  isothermals  show  the  aver- 
age temperature  belonging  to  the  places  which  they  connect ;  the 
monthly  and  season  isothermals  show  the  distribution  of  heat  through- 
out the  year. 

A  correct  delineation  of  the  isothermal  lines  of  the  globe  will, 
therefore,  show  most  clearly  the  general  deviations  from  the  astro- 
nomical climates  in  all  parts  of  the  Earth.  Where  the  isothermals 
bend  from  the  parallels  in  the  direction  of  the  Poles,  they  indicate 
an  average  temperature  higher  than  belongs  to  the  latitude ;  where 
they  approach  the  Equator,  they  indicate  a  temperature  lower  than 
belongs  to  the  latitude. 

II.  Deviations  from  Astronomical  Climates. 

1.  The  general  deviations  from  the  astronomical  climate  occur 
chiefly  in  the  middle  latitudes,  and  may  be  distinguished  as  primary 
and  secondary.  The  first  are  deviations  from  the  mean  annual  tem- 
perature belonging  to  a  given  latitude,  caused  mainly  by  the  influ- 
ence of  the  general  winds  and  the  marine  currents.  The  second  are 
departures  from  the  average  summer  and  ivinter  temperatures  belong- 
ing to  a  given  latitude,  occasioned  chiefly  by  differences  in  the  ab- 
sorbing and  radiating  power  of  land  and  water. 

2.  Local  deviations,  the  result  of  elevation,  occur  in  all  lati- 
tudes. They  consist  in  a  reduction,  proportionate  to  the  altitude,  of 
the  mean  temperature  belonging  to  the  latitude ;  while  the  periodical 
changes  remain  very  nearly  the  same.  On  an  average,  an  increase  of 
330  feet  in  altitude  diminishes  the  temperature  1°  Fahr. ;  hence  the 
rate  of  diminution  is  about  3°  to  1000  feet. 

In  tracing  the  isothermals,  according  to  Humboldt's  example,  the  local  influence 
of  altitude  is  usually  eliminated.  This  is  done,  as  in  the  accompanying  map,  by 
adding,  to  the  observed  temperature  of  a  place,  1°  for  every  333  feet  of  its  eleva- 
tion, thus  reducing  the  temperature  to  that  which  the  place  would  have  if  situated 
at  the  level  of  the  sea. 


1  From  the  Greek  isos,  equal,  and  therme,  heat. 


In  large  plateaus,  however,  the  effect  of  altitude  seems  to  be,  in 
some  measure,  counteracted  by  the  great  extent  of  absorbing  and 
radiating  surface  uplifted  into  the  atmosphere.  In  general  they  are 
considerably  warmer  than  the  isolated  summits  of  mountains  of  the 
same  altitude. 


III.  Influence  of  Winds  and  Marine  Currents. 

1.  Mode  of  Operation.  Winds  from  the  equatorial  regions  carry 
into  the  middle  latitudes  some  portion  of  the  heat  of  the.  tropical 
regions ;  while  polar  winds  bring  the  low  temperature  of  the  lati- 
tudes whence  they  come.  If,  therefore,  either  the  polar  or  the  equa- 
torial wind  prevails  throughout  the  year  in  a  particular  region,  a 
large  amount  of  heat  is  added  to,  or  subtracted  from,  that  which  be- 
longs to  the  latitude. 

Marine  currents  produce  a  similar  effect,  and  combine  with  the 
winds  to  cause  the  primary  modifications  of  the  astronomical  cli- 
mates. 

2.  The  observation  op  the  isothermals  traced  upon  the 
map,  brings  to  light  several  important  facts  in  regard  to  the  distri- 
bution of  temperature  on  the  globe. 

(1.)  The  greatest  modifications  of  the  astronomical  climates  occur 
in  the  northern  hemisphere,  the  isothermals  of  the  southern  hemi- 
sphere departing  far  less  from  the  parallels  of  latitude. 

(2.)  The  extreme  deviations  occur  on  the  coasts  of  the  north 
Atlantic,  western  Europe  being  very  much  warmer  than  eastern 
America  in  corresponding  latitudes.  The  difference  in  the  temper- 
ature of  the  opposite  coasts  increases  towards  the  pole. 

The  isothermal  of  50°  Fahr.,  which  passes  near  New  York,  on  the  40th  parallel 
of  latitude,  reaches  London,  on  the  opposite  side  of  the  Atlantic,  eleven  degrees 
farther  north.  The  isothermal  of  40°  Fahr.  passes  through  Canada  and  Nova 
Scotia,  near  the  46th  parallel,  but  lies  eighteen  degrees  farther  north  on  the  Euro- 
pean coast.  The  isothermal  of  30°  Fahr.  connects  central  Labrador  with  North 
Cape  in  Europe,  the  two  places  differing  in  latitude  by  twenty-one  degrees. 

Similar  deviations  take  place  in  the  north  Pacific,  but  the  differ- 
ences of  temperature  on  the  opposite  coasts  are  only  about  one  half 
as  great  as  on  the  Atlantic  coasts. 

In  the  northern  hemisphere,  the  winds  and  marine  currents  from  the  equatorial 
regions,  are  directed  towards  the  northeast,  thus  raising  the  temperature  of  the 
western  coasts  of  the  continents  ;  while  the  polar  winds  and  currents  strike  the 
eastern  coasts,  lowering  their  temperature. 

The  return-trades  of  the  Atlantic,  (see  page  79,  Top.  II.,  4,)  moving  northeast- 
ward over  the  warm  surface  of  the  Gulf  Stream,  absorb  a  portion  of  its  heat,  which 


QUESTIONS    ON    THE    MAP    OF    TEMPERATURE. 


Explain  the  coloring  of  the  map.  (See  margins,  pages  74,  75.)  Explain  the  lines  of  red  and 
blue. 

Explain  the  figures  near  the  isothermal  lines,  and  those  accompanying  the  names  of  places. 

Where  are  the  regions  of  greatest  heat  ?    What  is  the  average  temperature  of  these  regiorts  ? 

Near  what  cities  in  Asia,  Africa,  and  North  America  does  the  isothermal  of  70°  pass? 

Where  does  this  line  have  its  nearest  approach  to  the  equator? 

What  is  indicated  by  this  position  of  the  line?     (See  text  above.) 

How  do  you  account  for  the  comparatively  low  temperature  of  the  eastern  coast  of  Asia  V 
(See  Topic  III.,  1,  below,  and  Map  of  Winds,  pages  80,  81.) 

Where  is  the  isothermal  of  70"  farthest  from  the  equator? 

What  places  in  Australia,  Africa,  and  South  America  on  the  southern  isothermal  of  70°. 

Where  does  this  line  approach  nearest  to  the  equator? 

How  do  you  account  for  the  comparatively  low  temperature  on  the  Pacific  shores  of  South 
America?     (See  Map  of  Marine  Currents,  page  66.) 

Where  does  the  southern  isothermal  of  70°  depart  farthest  from  the  equator? 

How  is  tb;-  departure  to  be  explained?     (See  page  67,  IV.) 

Trace  ,ne  northern  isothermal  of  30°  across  Asia,  Europe,  and  North  America. 

iiow  does  its  position  in  the  interior  of  Asia,  Europe,  and  North  America  compare  with  its 
position  on  the  Atlantic  and  Pacific  coasts? 

How  do  you  explain  this  approach  to  the  equator?  (See  Topic  HI.,  1,  above,  and  Map  of 
Winds.) 

How  does  the  position  of  the  isothermal  of  30°  compare  on  opposite  sides  of  the  Atlantic? 


Explain  this  northward  deviation  on  the  eastern  coast.     (See  Topic  III.,  (2),  above.) 

How  does  the  deviation  of  the  isothermals  between  70°  and  30°  vary  from  south  to  north? 

What  important  places  in  Asia,  Europe,  and  North  America  lie  on  or  near  the  isothermal  of 
HP?    Of  50°?    Of  40°? 

Where  are  the  regions  of  greatest  cold  found  ? 

Wiiat  isothermal  forms  the  southern  boundary  of  these  regions? 

In  which  continent  is  this  frigid  region  most  extensive  ? 

How  do  the  isothermals  of  the  southern  hemisphere  compare  with  the  northern,  in  the  amount 
of  their  deviation  from  the  parallels? 

Near  what  parallel  is  the  equatorial  limit  of  drifting  ice  in  the  southern  hemisphere? 

Where  does  the  Antarctic  ice  advance  nearest  to  the  equator? 

Where,  in  the  open  seas,  is  the  southern  ice  limit  farthest  from  the  equator? 

How  far  southward  does  the  Arctic  ice  drift  on  the  western  shores  of  the  Atlantic? 

How  far  on  the  eastern  shores  ? 

How  do  the  temperatures  of  the  ocean  compare  with  those  of  the  continents  in  summer  ? 
(See  small  map  of  summer  isothermals.) 

Why  is  this?     (See  page  73,  Topic  IV  ,  1.) 

How  do  the  oceanic  and  continental  temperatures  compare  in  winter?    Why? 

Where  and  what  is  the  highest  average  summer  temperature  of  the  New  World? 

Of  the  Old  World?    How  do  these  averages  compare? 

Why  is  the  summer  of  northern  Africa  and  Arabia  so  much  warmer  than  the  corresponding 
regions  of  the  New  World?     (See  page  73,  Topic  IV.,  2.) 


PHYSICAL   CLIMATE. 


73 


they  spread,  with  their  own,  over  western  Europe  ;  but  the  return-trades  of  the 
Pacific  derive  little  or  no  additional  heat  from  the  Japanese  current,  which,  owing 
to  the  breadth  of  the  basin  it  has  to  traverse,  (see  page  65,  Topic  II,  2,)  becomes 
cool  before  reaching  the  American  shores. 

Thus  the  western  coast  of  North  America  has  its  temperature  augmented  by 
the  equatorial  winds  alone,  while  western  Europe  has  the  heating  influence  of  the 
winds  and  the  Gulf  Stream  combined ;  hence  the  higher  temperature  of  the  latter. 

In  the  southern  hemisphere,  branches  of  the  equatorial  current  sweep  along  the 
eastern  coasts,  while  the  polar  currents  strike  the  western  ;  the  former,  therefore, 
are  warmer,  and  the  latter  cooler,  than  the  latitude  would  indicate. 

(3.)  In  both  of  the  great  land-masses  of  the  northern  hemisphere 
—  Asia- Europe  and  North  America  — the  western  coasts  are  warmer 
than  the  eastern,  while  in  the  southern  hemisphere,  where  the  influ- 
ence of  the  marine  currents  from  the  Antarctic  predominates,  the 
eastern  coasts  are  the  warmer. 

(4.)  Zones  of  physical  climate  are  hounded  by  the  isothermals, 
while  the  astronomical  zones  are  limited  by  the  tropics  and  the  polar 
circles.  The  true  torrid  zone  may  be  regarded  as  terminating,  on 
each  side  of  the  equator,  at  the  isothermal  of  70°  Fahr.,  beyond 
which  the  characteristic  plants  and  animals  of  tropical  regions  disap- 
pear. The  temperate  zones  lie  between  the  isothermals  of  70°  and 
30°  Fahr.  ;  and  the  frigid,  extend  from  the  latter  to  the  poles. 

Thus  defined,  the  torrid  zone  is  broadest  in  Africa,  the  temperate 
in  Europe,  the  frigid  in  Asia.  Hence  it  appears  that,  on  an  aver- 
age, Africa,  the  largest  land  mass  within  the  tropics,  is  the  hottest 
of  the  continents ;  Europe,  the  smallest  of  the  northern  continents, 
is  the  warmest  in  the  temperate  zone  ;  while  Asia,  the  largest  of  all, 
is  the  coldest.  The  two  Americas,  both  in  regard  to  size  and  tem- 
perature, occupy  an  intermediate  grade. 

On  the  whole,  therefore,  we  may  conclude  that,  in  the  torrid  zone, 
the  greater  the  extent  of  the  land  the  higher  is  its  temperature, 
while  in  the  temperate  zone  the  reverse  is  true. 


IV.  Influence  of  Continents  and  Oceans. 

1.  Absorption  and  Radiation.  Water  has  a  great  capacity 
for  absorbing  heat,  and  but  feeble  conducting  power ;  hence  the  sea 
grows  warm  slowly  under  the  rays  of  the  sun  and  never  attains  a 
high  temperature.  It  also  radiates  heat  slowly,  and  as  fast  as  the 
surface  particles  become  cool,  they  sink  and  are  replaced  by  warmer 
ones  from  beneath ;  hence  the  cooling  process  is  as  gradual  as  the 
heating,  and  neither  produces  extremes  of  temperature. 

The  land  absorbs  the  solar  heat  rapidly,  and  the  surface  soon  at- 
tains a  high  temperature.  Especially  is  this  the  case  where  the  soil 
is  imperfectly  covered  with  vegetation,  as  in  treeless  plains  or  des- 
erts. But  when  the  sun  is  withdrawn  heat  radiates  with  rapidity, 
and  a  comparatively  low  temperature  is  soon  reached. 

2.  Result.  This  inequality  in  the  capacity  of  land  and  water  for 
absorbing  and  radiating  heat,  gives  rise  to  the  secondary  modifica- 
tions of  the  astronomical  climates,  affecting  more  especially  the 
amount  of  heat  in  the  various  seasons.  In  summer,  the  land  is 
warmer  than  the  sea  in  the  same  latitude ;  in  winter,  colder.  Along 
the  coasts  the  mingling  of  the  air  from  the  ocean  with  that  over  the 
land,  moderates  both  the  heat  of  summer  and  the  cold  of  winter ; 
hence  the  coasts  have  more  equable  season  temperatures  than  the 
interior. 

The.  following  table  exhibits  the  rapid  increase  in  the  difference  between  the 
summer  and  the  winter  temperature,  as  the  equalizing  influence  of  the  sea  is  lost 
by  distance.  It  gives  the  average  temperature  of  the  coldest,  and  of  the  warmest 
month  of  the  year,  in  places  situated  in  the  same  latitudes  but  at  different  dis- 
tances from  the  sea. 


Names  of  Places. 

[.at. 
62° 

Jan. 
Fahr. 

July. 
F'hr. 

Diff. 

Names  of  Places. 

Lat. 

Jan. 
Fahr. 

July. 
F'hr. 

62.4 

Diff. 

Faroe  Islands, 

39.0 

61.7 

22.7 

Eastport,  Maine, 

45° 

22.5 

399 

Bergen,  Norway, 

60° 

34.9 

60.3 

25.4 

Ft.  Snelling,  Minnesota, 

45° 

13.1 

73.4 

60.3 

St.  Petersburg,  Russia, 

60° 

15.6 

62.6 

47.0 

Bermuda,  Atlantic, 

32° 

32.6 

84.2 

21.6 

Yakutsk,  Siberia, 

62° 

-43.8 

62.2 

106.0 

Natchez,  Mississippi, 

32° 

62.2 

81.3 

29.1 

Penzance,  England, 

50° 

42.6 

62.0 

19.4 

Madeira,  Africa, 

32* 

636 

73.8 

10.8 

Barnaul,  Siberia, 

63s 

-  4.7 

67.1 

71.8 

Cairo,  Egypt, 

30° 

66.3 

86.6 

80.3 

The  extreme  temperatures  in  summer  and  winter  differ  to  a  still  greater  degree. 
The  highest  temperature  ever  observed  at  the  Faroe  islands  is  only  65.3°  Fahr, 
and  the  lowest  is  rarely  below  the  freezing  point.  In  St.  Petersburg,  2°  farther 
south,  extremes  of  92°,  and  —  40°  Fahr.  have  been  recorded.  Nearer  the  tropics, 
though  the  difference  between  the  seasons  is  less,  the  influence  of  the  continents 
and  the  oceans  is  still  apparent.  The  extremes  of  temperature  in  Madeira  show 
a  difference  of  only  20°  to  27°,  while  in  Egypt  the  difference  is  56°  Fahr. 

3.  Continental  and  Oceanic  Climates.  In  general  the 
climate  of  the  oceans  is  characterized  by  uniformity,  the  difference 
between  the  summer  and  the  winter  temperature  being  comparatively 
slight.  The  continental  climate,  on  the  contrary,  is  characterized  by 
sudden  changes,  and  extremes,  the  difference  between  the  summer  and 
the  winter  temperature,  in  middle  and  high  latitudes,  being  excessive. 

This  difference  in  land  and  sea  climates  is  sufficient  to  modify  the  average  tem- 
perature of  the  entire  globe.  In  consequence  of  the  great  preponderance  of  land 
in  the  middle  latitudes  of  the  northern  hemisphere,  and  of  water  in  the  southern, 
the  former  has  a  hot  summer,  and  the  latter,  at  the  same  period,  a  mild  winter. 
The  two  combined  give,  according  to  Prof.  Dove,  an  average  temperature  of  62.4° 
Fahr.  for  the  entire  globe,  in  July,  or  during  the  northern  summer.  In  like  manner 
the  winter  of  the  northern  hemisphere  is  colder  because  of  the  preponderance  of 
land ;  while  the  summer  of  the  southern  is  less  warm  because  of  the  excess  of 
water.  Hence  in  January,  or  during  the  southern  summer,  the  average  tempera- 
ture of  the  earth  is  but  54.3°  Fahr. ;  that  is,  8.1°  lower  than  in  July. 


ANALYSIS   OF  SECTION   III. 


I.  Contrasts  In  the  Same  Latitude. 

1.  Contrasts  Observed. 

a.  Qeneral  statement. 

b.  Examples. 

2.  Isothermal  Lines. 

a.  Definition  and  use. 

b.  Annual  isothermals. 

c.  Monthly  and  season  isothermals. 

II.  Deviations  from  Astronomical  Climates. 

1.  General  Deviations. 

a.  Where  occurring. 

b.  How  classed. 

c.  Character  and  cause. 

2.  Local  Deviations. 

a.  How  occasioned. 

b.  Where  occurring. 

c.  In  what  consisting. 

d.  Rate  of  diminution. 

e.  How  treated  in  tracing  isothermals. 

f.  Temperature  of  plateaus. 

III.  Influence  of  Winds  and  Marine  Currents. 

1.  Mode  op  Operation. 

!  Equatorial. 
Polar. 
Result  of  predominance  of  either, 
b.  Marine  currents. 


2.  Effects. 


Greatest  modifications  where. 

b.  Extreme  deviation  where.     Examples. 

Deviations  on  Pacific  coast. 
Explanation. 

Heating  influences  in  Atlantic. 

Heating  influences  in  Pacific. 

Conditions  in  southern  hemisphere. 

c.  Coasts  of  land  masses. 

d.  Average  temperature  of  oceans. 

e.  Zones  of  physical  climate. 

Limits.  Extent  in  the  several  continents. 
Temperature  of  the  continents  compared. 
Effect  of  greater  area  of  land. 

IV.  Influence  of  land  and  Water  Surface. 

1.  Absorption  and  Radiation  of  Heat. 

a.  Water  how  affected. 

b.  Land  how  affected. 

2.  Results. 

a.  General  character  of  seasons  of  continents. 

b.  Modifying  influence  on  coasts. 

c.  Table. 

d.  Comparison  of  extremes  of  temperature. 
8.  Continental  and  Oceanic  Climates. 

a.  Characteristic  of  oceanic  climates. 

b.  Characteristic  of  continental  climates. 

c.  Effects  on  average  temperature  of  globe. 


*"  "'1  Torrid  Zone  ;  mean,  temper-a  - 
lure  70*  degree.*-  of '  I&Jirenheit 
and   above  • 

Temperate  Zones,,     tempera,, 
tttre   between,  10  *  an,/   SO  * 
degrees- . 

ft-igld  Zones     temper-ature 
below  30'  degrees-  of' Rthrert- 
heit'. 

Hf./iort.s-    cf  greate.s-t  heat 
Kegion-f   of  greatest    cold 

The  arrow  .vhow  the  direr  - 
tiorb?  id*  tht  marine  eurrenzt . 
Counter-  Currents- 


J20 


and   the    C< 

ANINPAL  ISO 

33: 

T/te  figures'  near  the  line*-  in  the  main  m 
thos'e  hmv>  t/te  names-  of  p/aees-  ttn.f  net 
.vttsnmrr  trmpwitttrrs'   /•'■/'/■>:>•'■  nf**t  fn    rft>    <f\ 


£.Sando*  <*•  J. Khtmholtc  del. 


Entered  according  to  Aft  of  Congtvs.r  in.  the  Year  2872  hjr    SeHlmer.  Ji 


ig-S -i  .1-  in   f/i.-    iffth'f    itr'  thr    fl#HllfHW    of'  C-nrifire.W  at    Wh.fftfn<ftf>n    t\T. 


&■, Stern..  JSngr.* 


76 


THE   WINDS. 


IV.  — THE   WINDS. 

I.  Equilibrium  of  the  Atmosphere. 

1,  Conditions  of  Equilibrium.  The  atmosphere,  under  the 
influence  of  gravity,  tends  always  so  to  adjust  itself  as  to  be  in  a 
state  of  equilibrium,  the  chief  condition  of  which  is  a  uniform  density 
at  any  given  altitude,  the  density  diminishing  upward  with  the  de- 
creasing pressure  (See  page  69,  Topic  IV.)  But  the  continuance  of 
this  equilibrium  requires  uniformity  of  temperature,  as  well  as  of 
pressure,  in  all  parts  of  the  same  stratum  of  air. 

2.  Disturbance.  If  any  given  stratum,  whether  in  the  lower  or 
the  upper  air,  is  unequally  heated  in  different  parts,  the  equilibrium 
is  destroyed.  The  warmer  portion  expands  and  becomes  lighter ; 
and,  being  pressed  upon  by  the  adjacent  colder  and  heavier  air,  it 
rises,  and  its  place  is  occupied  by  the  latter. 

This  process  results  in  an  ascending  current,  from  the  region  of 
greatest  heat,  and  horizontal  currents  flowing  from  all  directions  to- 
wards that  region. 

This  is  exemplified  in  a  heated 
stove,  where  the  warm,  light  air, 
ascending  through  the  pipe,  is  re- 
placed by  a  steady  horizontal  cur- 
rent from  the  surrounding  cooler 
atmosphere. 

The  ascending  air,  having 
reached  a  stratum  of  equal 
density  with  itself,  ceases  to 
move  upward  ;  but,  if  still 
pressed  upon  by  a  current 
from  beneath,  it  is  diffused 
horizontally  in  all  directions. 
At  length,  gradually  sinking, 
it  may  help  to  feed  the  hori- 
zontal current  flowing  towards 
the  region  of  greatest  heat, 
thus  completing  a  circuit 
which  will  be  repeated  as  long 
as  the  inequality  of  tempera- 
ture continues. 


NORTH     POLE 


EQUATOR 


It  is  evident  that,  if  the  in- 
equality of  temperature  be 
constant,  the  resulting  circulation  will  be  constant  also ;  but  if  the 
overheating  of  a  given  region  be  only  temporary,  the  motion  will 
cease  as  soon  as  the  lighter  air  has  all  taken  its  position  above  the 
heavier,  and  the  equilibrium  is  restored  throughout  the  strata  to 
which  the  disturbance  extended. 


II.  General  Circulation  of  the  Atmosphere. 

1.  Winds  are  movements  of  the  atmosphere  caused  by  a  disturb- 
ance of  the  equilibrium  of  its  particles,  the  tendency  of  the  motion 
being  to  restore  that  equilibrium.  The  disturbances  are  mainly  oc- 
casioned by  differences  in  temperature,  and  in  the  amount  of  vapor 
held  in  suspension  by  the  air. 

Winds  may  be  grouped  in  three  classes,  namely  :  constant,  peri- 
odical, and  variable  winds.  The  first  class  embraces  the  trade  winds 
of  tropical  latitudes.  The  second  includes  the  diurnal  land  and  sea 
breezes,  and  the  monsoons  or  season  winds,  occurring  chiefly  in  trop- 
ical regions.  The  variable  winds  are  more  temporary  and  local,  and 
characterize  especially  the  temperate  and  high  latitudes. 


SOUTH     POLE 


WO.  32.      NORMAL  CIRCULATION  OF  THE  ATMOSPHERE. 


Winds  are  named  from  the  points  of  compass  whence  they  come. 

2.  General  Atmospheric  Currents.  In  the  vicinity  of  the 
equator,  where  the  average  annual  temperature  is  highest,  —  reach- 
ing 82°  Fahr.  and  upward, — the  atmosphere  is  at  its  minimum 
density  ;  and  the  density  gradually  increases,  with  the  diminishing 
temperature,  front  this  region  to  the  polar  latitudes. 

Set  in  motion  by  the  ascending  movement  of  the  lighter  equato- 
rial atmosphere,  the  cooler  and  heavier  air,  all  around  the  globe, 
flows  towards  this  zone  of  maximum  temperature.  There,  becom- 
ing, in  its  turn,  rarefied  by  the  intense  heat,  it  ascends  and  finally 
returns,  as  an  upper  current,  towards  the  poles. 

Cooled  by  its  expansion  in  ascending  and  its  advance  into  colder 
latitudes,  and  contracted  laterally  in  its  progress  towards  the  poles, 
this  upper  return  current  gradually  descends,  reaching  the  surface  of 
the  Earth  somewhat  beyond  the  tropics. 

Thence  a  part  returns  towards  the  equator,  the  remainder  con- 
tinuing  towards  the  poles,  partly  in  the  upper  air,  and  partly  as  a 

surface  current.  The  latter 
is  more  or  less  in  contact  with, 
and  opposed  by,  the  current 
setting  from  the  poles  towards 
the  zone  of  greatest  heat. 

Hence  from  the  permanent 
inequality  in  the  distribution 
of  heat  in  the  tropical  and 
polar  regions,  there  results,  in 
each  hemisphere,  a  constant 
circulation  of  the  atmosphere 
equator  consisting  of  (1.)  an  ascend- 
ing current,  in  the  zone  of 
highest  average  temperature ; 
(2.)  a  polar  current  flowing 
upon  the  surface,  from  each 
pole  towards  the  equator ; 
and  (3.)  a  return  current 
flowing  from  the  equator  to- 
wards each  pole,  partly  in  the 
upper  air  and  partly  on  the 
surface,  and  supplying  the 
constant  drain  of  the  polar 
current. 

The  above  diagram  is  designed  to  illustrate  this  normal  circulation  of  the  winds. 
The  arrows  parting  from  the  circumference  of  the  circle,  on  each  side  of  the 
equator,  represent  the  ascending  current  in  the  region  of  greatest  heat.  This 
region  is  designated,  for  reasons  given  below,  the  equatorial  belt  of  calms. 

The  polar  current,  which  replaces  the  ascending  air,  is  represented  by  the 
arrows  pointing  from  the  poles ;  while  those  pointing  towards  the  poles  represent 
the  return  currents. 

The  arrows  within  the  circumference  show  the  direction  of  the  prevailing  winds 
in  the  different  zones,  the  figures  indicating  latitudes.  Within  the  tropics  the 
winds  are  directed  westward  and  towards  the  equator.  Beyond  the  tropics  winds 
blow  both  towards  and  from  the  equator ;  while  near  the  poles  the  polar  winds 
predominate.  Belts  of  calms  occur  where  the  return-trade  descends  from  the 
upper  air. 

3.  Direction  of  Polar  and  Return  Currents.  Were  the 
Earth  at  rest,  and  its  surface  uniform,  these  currents  would  doubt- 
less follow  the  meridians  to  and  from  the  equator.  But  the  rotary 
motion 1  common  to  both  the  terrestrial  globe  and  its  atmosphere, 
causes  the  polar  currents,  as  they  near  the  equator,  to  turn  more  and 
more  towards  the  west ;  hence  they  become  northeasterly  winds  in 
the  northern   hemisphere  and  southeasterly  winds  in  the  southern. 

l  See  explanation  of  the  direction  of  marine  currents,  page  65. 


THE  WINDS. 


77 


The  return  currents,  on  the  contrary,  advancing  from  equatorial  to 
polar  latitudes,  are  deflected  towards  the  east,  becoming  south- 
westerly winds  in  the  northern  hemisphere  and  northwesterly  winds 
in  the  southern  hemisphere. 

Again,  the  continental  reliefs,  and  the  relative  positions  of  the 
land-masses  and  oceans,  cause  many  local  modifications  in  the  direc- 
tion of  these  general  currents. 

4.  Wind  Zones.  The  general  law  of  atmospheric  circulation 
just  noticed,  gives  rise  to  three  distinctly  marked  wind  zones,  on 
each  side  of  the  Equator;  namely:  —  (1.)  the  zone  of  constant 
winds,  extending  to  latitude  25°  or  30°  ;  (2.)  the  zone  of  variable 
winds,  with  alternate  polar  and  equatorial  currents  dominating,  ex- 
tending thence  to  latitude  60°,  or  near  the  polar  circles ;  and  (3.)  the 
zone  of  prevailing,  though  not  constant,  polar  winds:  (See  Fig.  32, 
and  the  Map  of  the  Winds,  page  80,  81.) 


III.  Trade  Winds  and  Calms. 

1.  Trade  Winds.  The  constant,  gentle,  northeasterly  and  south- 
easterly winds,  occupying  a  belt  of  25°  or  30°  of  latitude  on  each 
side  of  the  Equator,  are  designated  the  trade  winds. 

It  was  this  constant  and  gentle  wind  which  carried  the  navigator 
Magellan  across  the  Pacific,  and  gave  this  ocean  the  name  it  has 
since  retained ;  and  which  subsequently  bore  the  Spanish  treasure- 
ships,  from  the  Mexican  and  Peruvian  ports,  to  their  destination  in 
the  Philippine  Islands.  The  same  unchanging  westerly  wind,  ob- 
served in  the  Atlantic  by  the  companions  of  Columbus,  filled  their 
minds  with  the  fear  that  they  could  never  accomplish  a  homeward 
voyage. 

The  trades  blow  with  entire  regularity  only  upon  the  open  sea, 
the  course  and  character  of  the  winds  elsewhere  being  modified  by 
the  continental  reliefs  or  other  local  influences.  The  continents, 
on  account  of  the  elevation  of  their  surface,  partially  intercept  the 
general  atmospheric  currents,  and,  being  also  more  heated  than  the 
adjacent  oceans,  they  modify,  or  even  overcome,  the  trades  in  their 
immediate  vicinity. 

Owing  to  this  disturbing  influence,  the  trades,  both  in  the  Atlan- 
tic and  the  Pacific,  begin  to  blow  regularly  only  at  a  considerable 
distance  west  of  the  continents.  Thence  they  sweep,  without  inter- 
ruption, over  the  ocean  basins,  at  a  nearly  uniform  rate  of  from  15 
to  18  miles  per  hour.  In  the  northern  half  of  the  Indian  Ocean 
the  trades  are  suspended  entirely  during  the  northern  summer,  but 
resume  their  sway  in  winter.     (See  Monsoons,  page  78.) 

2.  Equatorial  Calms.  The  boundary  between  the  northeast 
and  southeast  trades,  is  formed  by  the  zone  of  the  ascending  cur- 
rent, frt  "n  4°  to  6°  in  breadth,  adjacent  to  the  thermal  Equator. 
The  mean  position  of  this  zone  is,  in  the  Atlantic,  between  3°  and 
9°  north  latitude ;  in  the  Pacific,  between  4°  and  8°  north.  In  the 
continents  it  is  usually  found  between  3°  south,  and  4°  north  lati- 
tude. 

Here  the  ascending  current  overpowers  the  horizontal ;  and,  as 
the  upward  motion  is  not  perceptible  to  the  observer,  the  atmosphere 
seems  to  be  in  a  state  of  rest ;  hence  this  belt  is  designated  the  Zone 
of  Equatorial  Calms.  (See  Fig.  32,  and  Map  of  the  Winds,  page 
80.) 

The  apparent  equilibrium  of  the  air,  however,  is  very  easily  dis- 
turbed. Descending  currents,  sudden  gusts  of  wind  from  any  direc- 
tion, whirlwinds,  and  hurricanes,  are  of  frequent  occurrence.  Hence 
this  belt  is  sometimes  called  the  Equatorial  zone  of  variable  winds. 


In  each  ocean  this  zone  is  considerably  broader  at  the  east  than  at 
the  west. 

3.  Tropical  Calms.  At  the  tropical  limits  of  the  trades,  also 
(see  Map  of  the  Winds'),  there  are  zones  of  calms,  designated  the 
Calms  of  Cancer  and  the  Calms  of  Capricorn.  These,  however,  are 
less  defined  than  the  equatorial  calms.  They  occupy  a  belt  of  a  few 
degrees,  in  which  the  return  current  of  the  upper  air,  called  the  re- 
turn-trade, first  appears  at  the  surface  of  the  Earth  ;  and  where  it 
divides,  a  part  continuing  towards  the  poles,  and  the  remainder  reen- 
tering the  trade  zone  and  returning  to  the  Equatorial  calm  belt. 

4.  Oscillation  op  Trades  and  Calms.  The  position  of  the 
trades,  and  of  the  intervening  and  adjacent  calms,  changes  with  the 
seasons,  all  advancing  northward,  and  retiring  southward,  with  the 
apparent  motion  of  the  Sun.  The  extreme  northward  position  of 
the  trades  is  reached  in  August  and  September,  and  the  southward 
in  March  and  April.  (See  diagram,  Limits  of  Trades,  in  Map  of 
Winds.) 

In  the  oceans,  the  belt  of  Equatorial  calms  is  north  of  the  Equator 
in  all  seasons ;  and  the  Calms  of  Cancer  are  farther  from  the  Equa- 
tor than  the  Calms  of  Capricorn.  These  positions  indicate  a  higher 
average  temperature  in  the  northern  hemisphere  than  in  the  south- 
ern. 

5.  General  Land  Winds.  The  trades,  as  has  been  observed, 
lose  their  constancy  of  character  under  the  influence  of  the  continen- 
tal reliefs ;  still  prevailing  easterly  winds  occur,  so  far  as  known,  on 
the  great  plains  within  the  zone  of  trades.  They  are  felt  in  a  part 
of  the  Sahara  ;  and  in  the  basin  of  the  Amazon  they  sweep,  without . 
interruption,  across  almost  the  entire  breadth  of  the  continent. 
Though  gentle,  in  the  east,  like  the  trades  of  the  ocean,  their  force 
increases  considerably  near  their  western  limit. 

Humboldt  found  at  the  base  of  the  Andes,  the  east  wind  so  strong  that  one  could 
scarcely  stand  against  it ;  and  it  is  said  that,  on  account  of  the  constant "  east 
wind,  the  voyage  up  the  Amazon,  against  the  powerful  current,  is  made  quite  as 
rapidly  as  that  down  the  stream. 


ANALYSIS  OP  SECTION   IV. 

I.  Equilibrium  of  Atmosphere. 

1.  conditioks  of  equilibrium  of  alr. 

2.  Disturbance  op  Equilibrium. 

a.  Effect  of  inequality  of  temperatuw. 

b.  Resulting  currents. 

.  c.  Course  of  ascending  air. 

d.  Effect  if  inequality  be  permanent. 

e.  Effect  if  inequality  be  temporary. 

II.  General  Circulation  of  Atmosphere. 

1.  Winds. 

a.  Definition. 

b.  Classes. 

2.  General  Currents. 

a.  Zone  of  minimum  density. 

b.  Movement  of  air  towards  this  zone. 

c.  Movement  of  air  from  this  zone. 

d.  General  currents  resulting. 

e.  Explanation  of  Fig.  32. 

3.  Directions  of  General  Currents. 

a.  Probable  direction  in  absence  of  disturbing  causes, 
b    Effects  of  the  rotation  of  the  Earth. 

c.  Direction  of  polar  currents. 

d.  Direction  of  return-currents. 

e.  Other  causes  of  modification. 

4.  Wind  Zones. 

a.  Number. 

b.  Names  and  position. 

III.  Zone  of  Trades  and  Calms. 

1.  Trade  Winds. 

a.  Definition.    By  whom  first  observed. 

b.  Where  occurring  regularly. 

c.  Place  of  beginning  on  oceans. 

d.  Velocity. 

e.  Trades  of  the  Indian  Ocean. 


78 


WINDS. 


2.  Equatorial  Calms. 

a.  Position  in  regard  to  trades. 

b.  Breadth  of  calm  belt. 

c.  Cause  of  calm  belt. 

d.  Disturbance  of  equilibrium. 
8.  Tropical  Calms. 

a.  Position  in  regard  to  trades. 

b.  Breadth  and  character  of  region. 

4.  Oscillations  of  Trades  and  Calms. 

a.  Change  of  position  caused  how. 

b.  When  farthest  northward. 

c.  When  farthest  southward. 

d.  Position  of  calm  belt  in  regard  to  equator. 

5.  General  Land  Winds. 

a.  Character  of  trades  on  land. 

b.  Winds  of  Sahara,  and  Amazon  basin. 


V.  —  WINDS.    (  Continued.') 


I.  Periodical  Winds. 

1.  Monsoons.  The  name  monsoon,  from  the  Arabic  word  mous- 
sim,  season,  is  applied  to  the  periodical  winds  which  replace  the 
trades,  in  the  northern  half  of  the  Indian  Ocean,  and  in  the  adjacent 
portions  of  the  Pacific.  During  the  northern  summer  the  wind 
blows  from  the  southwest,  during  the  opposite  season  from  the  north- 
east. The  monsoons  are  due  to  the  unequal  heating,  in  different 
seasons,  of  the  great  land-masses  which  inclose  the  Indian  Ocean. 

The  extent  of  land  within  the  tropics,  and  the  position  of  vast' 
masses  on  opposite  sides  of  the  Equator,  is  such  as  to  intensify  to  the 
greatest  degree  their  disturbing  influence  upon  the  atmospheric  cur- 
rents. Only  in  the  interior  of  the  Indian  Ocean,  south  of  the  Equa- 
tor, does  the  trade  wind  blow  regularly  throughout  the  year. 

During  the  northern  summer,  southern  Asia,  under  the  rays  of  the  vertical  Sun, 
becomes  intensely  heated  ;  and  the  cooler  and  denser  air  of  the  adjacent  ocean, 
and  of  southern  Africa,  flows  towards  it,  producing  the  southwest  monsoon,  which 
lasts  from  April  or  May  to  September  or  October.  The  time  of  its  beginning  and 
its  close  varies  in  different  latitudes,  according  to  the  time  at  which  the  sun  is 
vertical  in  each. 

During  the  southern  summer,  southern  Africa  being  under  the  vertical  Sun  and 
intensely  heated,  the  cooler  air  of  the  surrounding  seas,  and  of  southern  Asia,  flows 
towards  it.  This  produces  the  northeast  monsoon,  which  lasts  from  October  or 
November  to  April.  This  monsoon  is,  in  fact,  only  the  regular  northeast  trade 
wind  somewhat  intensified. 

A  similar  exchange  takes  place  between  Asia  and  Australia,  but  it  is  less 
marked,  owing,  perhaps,  to  the  great  islands  lying  between  these  continents. 

The  period  of  transition  of  the  monsoons,  in  spring  and  autumn,  is  marked  by 
sudden  and  violent  gales,  and  terrific  thunder  storms.  Destructive  hurricanes, 
also,  are  of  frequent  occurrence. 

Narrow  monsoon  belts  occur  in  the  Atlantic  along  the  coast  of  Af- 


rica, and  of  Brazil ;  also  on  the  Pacific  coasts  of  North  and  South 
America  (See  Map  of  the  Winds)  ;  but  the  phenomena  they  exhibit 
are  of  a  much  less  striking  character.  On  the  African  coast,  in  gen- ' 
eral,  the  winds  blow  from  sea  to  land  in  summer,  from  land  to  sea  in  • 
winter ;  on  the  Brazilian,  the  wind  is  from  the  northeast  in  summer, 
while  in  winter  the  southeast  trade  resumes  its  sway.  The  mon- 
soons of  the  Pacific  coast  of  America  blow  from  the  northwest  and 
north  during  the  southern  summer  ;  from  the  southwest  and  south 
during  the  northern. 

2.  Diurnal  Land  and  Sea  Breezes  occur  along  all  coasts, 
whether  in  the  zone  of  trades  or  of  variable  winds ;  but  the  phe- 
nomenon is  more  strongly  marked  in  the  tropical  regions,  and  in  the 
summer  of  the  temperate  latitudes,  because  of  the  greater  difference 
in  the  temperature  of  land  and  sea  by  day  and  by  night. 

During  the  hottest  part  of  the  day  the  air  over  the  land  frequently 
reaches  a  temperature  of  100°  Fahr.,  and  even  more,  while  that  over 
the  sea  rarely  rises  above  80°.  During  the  night  the  land  radiates 
its  heat  with  such  rapidity  that,  towards  morning,  its  atmosphere 
may  be  from  10°  to  15°  colder  than  that  of  the  sea. 

Soon  after  sunrise,  the  land  being  warmer  than  the  sea,  a  sea 
breeze  sets  in,  which  increases  in  force  until  about  three  o'clock, 
when  the  difference  of  temperature  is  greatest.  It  then  gradually 
diminishes  until  about  sunset,  when,  the  temperature  of  the  land  and 
sea  having  become  equal,  the  atmosphere  is  at  rest,  the  calm  con- 
tinuing for  an  hour  or  more. 

Soon  the  land  becomes  cooler  than  the  sea,  and  a  gentle  breeze 
from  the  former  sets  in.  It  increases  in  force  as  the  night  advances, 
becoming  strongest  a  little  before  morning,  when  the  temperature  of 
the  land  is  lowest ;  after  which  it  rapidly  dies  away,  ?jid  is  suc- 
ceeded by  a  calm,  to  be  soon  replaced  by  the  sea  breeze. 

Similar  diurnal  breezes  occur  on  the  shores  of  all  great  lakes,  and  also  at  the 
foot  of  high  mountains.  The  inclined  surface  of  the  mountain  slopes  has,  while 
under  the  rays  of  the  Sun,  a  higher  temperature  than  the  atmosphere,  at  corre- 
sponding altitudes,  above  the  lowlands.  Hence  it  becomes  the  natural  channel  for 
the  ascending  currents  of  warm  air  from  the  adjacent  plains;  and,  consequently, 
a  breeze  ascends  the  valleys,  towards  the  mountains,  during  the  hottest  part  of  the 
day. 

3.  Local  Land  Winds,  of  a  peculiar  character,  occur  more  or 
less  periodically,  in  different  parts  of  the  warm  zones.  The  Sirocco 
of  the  Mediterranean  shores,  the  Khamsin  of  Egypt,  the  Samiel  or 
Simoom  of  Syria  and  Arabia,  and  the  Harrnattan  of  Guinea,  are 
local  names  for  a  violent,  hot  and  dry  wind  from  the  adjacent  deserts. 

In  Guinea  the  desert  wind  blows  from  the  northeast  and  east ;  on 


QUESTIONS    ON   THE   MAP    OF   THE   WINDS.     (See  Map,  pages  80,  81.) 


Explain  the  coloring  of  this  map.    (See  bottom  of  map.) 

How  is  the  direction  of  the  winds  indicated?     (See  explanation  of  arrows.) 

How  are  periodical  winds  represented  ? 

In  which  ocean  does  the  belt  of  trades  extend  farthest  from  the  equator? 

On  which  shore  of  the  Atlantic  and  the  Pacific  is  the  northeast  trade  belt  broadest? 

Where  is  the  southeast  trade  belt  broadest? 

In  what  part  of  the  oceans  are  the  equatorial  calm  belts  most  extensive  ? 

What  name  is  given  to  the  region  of  equatorial  calms  in  the  Atlantic? 

What  (see  diagram  in  left  hand  margin)  is  the  summer  limit  of  the  northeast  trades  in  the 
Atlantic  ?    The  winter  limit  ? 

What  are  the  summer  and  winter  limits  of  the  southeast  trades? 

In  what  part  of  the  Indian  Ocean  do  the  trades  blow  with  regularity? 

Near  what  islands  are  the  northeastern  and  southeastern  limits  of  the  Pacific  monsoon 
region  ? 

What  are  the  directions  of  the  monsoons  in  the  seas  adjacent  to  Australia? 

What  are  their  directions  in  the  Asiatic  and  African  seas? 

In  what  part  of  the  year  does  each  current  prevail  ? 

Why?     (See  Monsoons,  above.) 

What  are  the  directions  of  the  winds  in  the  Brazilian  monsoon  belt? 

What  winds  prevail  in  the  southern  part  of  South  America? 

What  is  the  direction  of  the  winds  on  the  west  coast  of  South  America? 


When  does  each  direction  prevail  ? 

What  is  the  direction  of  the  wind  in  the  portion  of  the  Pacific  near  the  Isthmus  of  Panama? 

What  is  the  usual  direction  of  the  winds  on  the  Atlantic  shores  of  Africa? 

What  are  the  prevailing  directions  of  the  wind  between  the  parallels  of  30°  and  60°  ? 

How  do  these  winds  differ  in  character  ? 

What  is  the  direction  of  the  polar  winds  in  eastern  North  America  and  eastern  Asia? 

In  western  Asia,  Europe,  and  northwestern  North  America  ? 

What  causes  this  difference  in  direction?     (See  page  79,  Topic  II.,  3.) 

What  is  the  direction  of  the  prevailing  winds  in  the  Arctic  seas  ? 

What  is  the  position  of  the  hurricane  region  of  the  New  World  ? 

Where  are  the  hurricane  regions  of  the  Old  World  ? 

Where  do  the  typhoons  of  the  Asiatic  seas  originate  ?    What  is  their  course  ? 

Where  do  the  Mauritius  hurricanes  start,  and  in  what  direction  do  they  move  ? 

What  is  the  place  of  origin  of  the  West  India  hurricanes  ?    What  is  their  course  ? 

What  (see  diagram  in  the  right  hand  margin)  are  the  intervening  directions  in  a  change  of 
the  wind,  in  the  northern  hemisphere,  from  northeast  to  southwest? 

What  is  the  effect  of  this  change  on  the  thermometer  and  the  barometer  ? 

What  is  the  order  and  effect  of  a  change  from  southwest  to  northeast? 

What  is  the  order  and  effect  of  a  change,  in  the  southern  hemisphere,  from  a  northwest  to 
a  southeast  wind  ? 

From  a  southeast  to  a  northwest  wind? 


WINDS. 


79 


the  Mediterranean  shores,  from  the  southeast,  south,  and  southwest ; 
in  Syria,  from  the  south  and  southeast ;  and  in  Arabia,  from  the  in- 
terior towards  all  points  of  the  compass.  The  Sirocco,  advancing 
across  the  Mediterranean,  is  felt  in  Sicily  and  Italy  ;  and  is  known 
in  southern  Spain  as  the  Solano  or  Levanter. 

The  name,  Khamsin,  meaning  fifty,  indicates  the  length  of  the  season,  —  about 
fifty  days,  including  the  month  of  May  and  a  part  of  April  and  June,  —  during 
which  this  wind  may  blow.     Simoom  means  hot  as  well  as  poisonous. 

These  desert  winds  are  not  continuous,  but  occur  at  intervals  during  the  two  or 
three  months  of  greatest  heat,  lasting  from  one  to  fifteen  days  at  a  time.  They 
usually  blow  in  successive  blasts,  which  differ  in  temperature,  sometimes  by  more 
than  20°  Fahr.,  and  alternate  with  great  rapidity.  Dry,  laden  with  the  impalpable 
dust  of  the  desert,  and  subject  to  such  rapid  alternations  of  temperature,  they  are 
exceedingly  oppressive  and  exhausting  to  the  human  system,  and  not  infrequently 
cause  death  by  prostration. 

The  Etesian  Winds  are  northeasterly  and  easterly  winds  which 
blow,  during  the  latter  part  of  summer,  over  Greece,  the  Archipel- 
ago, and  the  Mediterranean,  towards  the  continent  of  Africa.  They 
commence  near  the  middle  of  July,  when  the  heat  is  greatest,  and 
continue  until  September,  blowing  only  in  the  day-time. 

The  Northers  of  Texas  are  violent,  cold,  dry  winds,  which  descend 
from  the  upper  air,  and  occur  chiefly  in  winter.  They  sweep  over 
Texas,  Lousiana,  and  the  table-lands  of  Mexico,  sometimes  carrying 
their  cold  blasts  even  to  the  Antilles,  where  they  present  a  striking 
contrast  to  the  gentle  and  genial  trade  winds. 


II.  Zone  of  \ariable,  or  Alternating  Equatorial  and  Polar,  Winds. 

1.  Prevailing  Currents.  Within  this  zone,  which  extends 
from  the  vicinity  of  the  tropics  to  the  polar  circles,  the  winds  are 
not  periodical,  but  blow  during  the  year  from  every  quarter  of  the 
horizon,  without  apparent  order.  Two  general  currents,  however, 
the  polar  winds  and  the  return-trades,  predominate  to  such  an  ex- 
tent that  they  may  be  considered  the  prevailing,  or  normal  currents, 
of  these  latitudes. 

Differing  in  temperature,  and  flowing  side  by  side,  or  one  above 
the  other,  but  in  opposite  directions,  they  constantly  encounter  each 
other  and  struggle  for  the  mastery.  Their  conflicts  produce  the  fre- 
quent storms  which  characterize  these  zones  ;  and  the  displacement 
of  the  one  by  the  other  always  involves  a  marked  change  of  weather. 
The  return- trade  brings  heat,  and  clouds  or  rain  ;  but  the  polar  winds 
bring  cold,  dry  weather,  a  bracing  air,  and  a  clear  sunny  sky. 

The  other  winds  blowing  in  these  zones  are  either  the  transition 
winds,  which  occur  during  the  displacement  of  one  current  by  the 
other ;  or  are  the  result  of  the  deflection  of  these  normal  currents, 
by  mountain  ranges  or  other  peculiarities  of  the  continental  reliefs. 

2.  Succession  op  Winds.  The  return-trades  and  the  polar 
winds  usually  displace  each  other  in  an  order  indicated  by  Prof. 
Dove,  and  called  by  him  the  law  of  the  rotation  of  the  winds.  This 
order  of  succession  must  not  be  confounded  with  the  veering  of  the 
wind  from  point  to  point  in  a  revolving  storm,  which  has  a  different 
origin.     (See  Revolving  Storms,  page  82.) 

In  the  northern  hemisphere,  generally,  when  the  return-trade  is  dis- 
placed by  the  polar  current,  the  wind  blows  successively  from  the 
west,  the  northwest,  and  the  north,  and  settles  in  the  northeast.  In 
eastern  North  America,  however,  it  settles  in  the  northwest.  (See 
Topic  3,  below.)  W,hen  the  polar  wind  is  displaced  by  the  return- 
trade,  the  successive  changes  are  to  the  east,  southeast,  south,  and 
finally  to  the  southwest.    (See  diagram  in  Map  of  Winds.) 

In  the  southern  hemisphere  the  order  of  transition  is  reversed,  as  is 
also    the    character   of   the    currents.     The  northwest  wind  is  the 


warm,  moist  return-trade ;  while  the  southeast  is  the  cold,  dry  polar 
wind.  The  transition  is  from  the  northwest  by  the  west,  southwest 
and  south  to  the  southeast ;  and  from  the  southeast  by  the  east, 
northeast,  and  north,  to  the  northwest. 

The  effect  of  the  transition  of  the  winds  is  manifest,  both  in  the 
density  and  the  temperature  of  the  air.  When  the  return-trade 
blows,  the  air  being  warm,  moist  and  light,  the  thermometer  is 
high  and  the  barometer  low.  When  it  is  displaced  by  the  polar 
current,  the  thermometer  falls  and  the  barometer  rises. 

3.  The  STARTING  points  OP  the  POLAR  winds  are  in  the  centres 
of  lowest  temperature,  on  the  Arctic  shores  of  Asia  and  North 
America.     (See  Map  of  Temperature,  pages  74,  75.) 

The  expansion  of  these  two  continents  at  the  north  is  such  that  a 
great  extent  of  land  lies  in  the  immediate  vicinity  of  the  Arctic 
circle.  This  large  area  of  Arctic  land,  combined  with  the  long 
nights  of  a  winter  lasting  nearly  or  quite  half  the  year,  converts  the 
northern  regions  of  Asia  and  North  America  into  vast  refrigerators, 
where  the  atmosphere,  during  the  northern  winter,  is  reduced  to  its 
minimum  temperature  and  its  greatest  density. 

From  here  the  cold,  heavy  air  presses  towards  the  oceans  at  the 
east  and  the  west,  and  the  more  southerly  warm  lands.  Hence  East- 
ern Asia  and  North  America,  especially  in  high  latitudes,  receive 
their  coldest  winds  from  the  northwest  and  north ;  while  Western 
Asia  and  Europe  receive  them  from  the  northeast. 

As  the  cold  air  advances  towards  the  equator,  and  falls  increas- 
ingly under  the  influence  of  the  Earth's  rotary  motion,  it  tends  more 
and  more  to  become  everywhere  a  northeast  wind.  But  in  North 
America  the  great  barrier  of  the  Rocky  Mountains,  which  is  high- 
est in  the  middle  latitudes,  turns  it  out  of  its  southwesterly  course, 
and  deflects  it  towards  the  southeast ;  hence  throughout  our  Atlantic 
seaboard,  even  to  the  sub-tropical  regions,  the  cold,  dry  winds  are 
from  the  northwest. 

This  exceptional  direction  of  the  polar  winds  in  eastern  North  America,  is 
shown  on  the  Map  of  the  Winds. 

As  the  sun  advances  northward  in  the  spring,  his  genial  beams  im- 
part a  constantly  growing  warmth  to  the  Arctic  lands  ;  and  the  rap- 
idly increasing  length  of  the  days  accelerates  the  change  from  a  low 
to  a  high  temperature.  Thus  the  fountains  of  the  cold  winds  are 
gradually  dried  up  ;  the  pressure  of  the  northern  air  is  diminished  ; 
and,  during  the  summer,  the  warm  gentle  return-trades  have  almost 
undisputed  sway  nearly  to  the  Arctic  circle. 

4.  Range  and  Effects.  The  polar  currents,  having  their  ori- 
gin in  the  Arctic  lands,  take  their  course,  in  general,  over  the  surface 
of  the  continents,  while  the  return-trades  prevail  upon  the  oceans. 
This  fact  accounts  for  the  low  average  temperature  of  the  interior 
of  the  continents,  in  middle  latitudes,  in  comparison  with  that  of  the 
oceans,  as  indicated  by  the  isothermal  lines. 

In  the  middle  and  northern  portions  of  the  zone  of  variable  winds, 
the  return-trades  are  the  dominant  winds  during  the  summer,  the 
polar  winds  during  the  winter.  The  period  of  transition,  occupying 
several  weeks  following  the  equinoxes,  is  one  of  almost  incessant 
conflict ;  hence  the  severe  storms,  and  frequent  changes  of  wind  and 
weather  which  characterize  those  seasons  of  the  year. 

The  final  establishment  of  the  return-trade,  with  its  genial  temper- 
ature and  fertilizing  showers,  ushers  in  the  summer ;  its  final  retreat 
before  the  polar  winds,  toward  the  close  of  the  year,  opens  the  winter. 
The  continuance  of  the  return-trade  beyond  its  average  time  of  dis- 
placement produces  a  "  late  autumn,"  and  that  of  the  polar  winds, 
a  "  late  spring." 


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marks  the  pouU    ot'  t/te    compass  towarxis   which  tJte   Wind 
mrsves,    the   opposite    end    thszt   from    which   it  blows . 
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<A    "^^-      Mjt*nsoonst     or    Set/son  Winds  ,    blowing 
perfi't/y-'iifiv  in  one  or  ths  other  dirrcthtn  . 


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82 


REVOLVING  STORMS. 


ANALYSIS  OF   SECTION  V. 

I.  Periodical  Winds. 

1.  Monsoons. 

a.  Definition,  direction,  and  cauBe. 

b.  Monsoons  of  Indian  Ocean  explained.    Transition. 
c    Minor  monsoon  belts.    Position  and  character. 

2.  Land  and  Sea  Breezes. 

a.  Where  occurring  and  why. 

b.  Daily  alternation  of  temperature  within  the  tropics. 

c.  Sea  breeze,  when  and  how  caused.     Land  breeze. 

d.  Inland  diurnal  breezes. 

3.  Local  Periodical  Winds. 

a.  Desert  winds.    Names  and  character.    Directions. 

When  and  how  occurring.    Effects. 

b.  Etesian  Winds.    Northers. 

II.  Zone  of  Variable  Winds. 

1.  Prevailing  Currents. 

a.  Character  of  winds  in  this  zone. 

b.  Normal  currents  of  this  zone. 

c.  Effect  of  juxtaposition  and  opposite  directions. 

d.  Character  of  other  winds. 

2.  Succession  op  Winds. 

a.  Law  of  rotation  signifies  what.     By  whom  discovered. 

b.  Order  of  displacement  in  northern  hemisphere. 

c.  Order  of  displacement  in  southern  hemisphere. 

d.  Effects  of  transition  how  manifested. 
&  Starting  Point  of  Polar  Winds. 

a.  Effect  of  expansion  of  lauds  in  northern  regions. 

b.  Atmosphere  of  northern  lands  in  whiter 

c.  Motion  of  cold,  heavy  air. 

d.  Direction  of  winds  in  eastern  Asia  and  North  America. 

e.  Direction  of  winds  in  western  Asia  and  Europe. 

f.  Effect  of  approach  of  current  to  equator. 

g.  Exception  in  North  America. 

h.  Effect  of  advance  of  sun  northward. 

4.  Sweep  op  Prevailing  Currents. 

a.  Path  of  polar  winds. 

b.  Path  of  return  trades. 

c.  Effect  on  comparative  temperature  of  continents  and  ocean*. 

d.  Dominant  winds  iu  different  seasons. 

e.  Period  of  displacement. 

f.  Effect  of  final  establishment  of  either  current. 

g.  Effect  of  unusual  prolongation  of  either. 


N.  Hemisphere. 


VI.  —  REVOLVING   STORMS. 

I.  Introduction. 

When  currents  of  air,  moving  in  different  directions,  encounter 
each  other,  they  produce  a  ro- 
tary motion  in  the  atmosphere, 
such  as  is  seen  in  the  small 
whirlwinds  which  often  lift  Up 
the  dust  of  our  streets  in  sum- 
mer. Such  a  movement  on  a 
grand  scale  is  a  revolving  storm 
or  cyclone,1  to  which  various 
local  names  are  given.  When 
the  conflicting  currents  of  air 
are  of  very  different  tempe- 
ratures, these  storms  are  usu- 
ally accompanied  by  the  con- 
densation of  vapor,  producing 
rain,  snow,  or  hail ,  and  not  in- 
frequently by  vivid  electrical 
discharges. 

Cyclones  vary  in  the  nature 
and  violence  of  their  phenom- 
ena, according  to  their  imme- 
diate cause.     The  most  remarkable  for  violence,  and  for  the  regular- 
ity of  their  course,  are  the  hurricanes  of  the  West  Indies,  and  of 


S.  Hemisphere. 


FIG.   33.      COURSE  OF   CYCLONES. 


1  From  the  Greek  kuklos,  a  circle. 


Mauritius  in  the  Indian  Ocean;  the  typhoons  of  the  South  China 
Sea  ;  and  the  cyclones  of  the  Gulf  of  Bengal. 

The  peculiar  position  of  these  great  cyclone  regions  of  the  globe, 
at  the  southeast  of  the  largest  continents  and  under  the  tropics,  seems 
to  indicate  that  these  storms  are  the  result  of  a  conflict,  in  the  upper 
air,  between  the  general  winds  of  the  temperate  and  tropical  zones, 
intensified  by  the  disturbing  influence  of  the  great  land  masses. 


II.  Law  of  Storms. 

1.  Motions.  Observations  upon  the  winds  and  the  pressure  of 
the  air,  during  cyclones,  have  been  collected  with  great  care  and  in- 
dustry by  Mr.  Redfield  of 


NORTH   HEMISPHERE. 

WIND 

EAST 


SOUTH    HEMISPHERE. 

WIND 


New  York,  Governor  Reid 
of  Bermuda,  Piddington 
of  Calcutta,  and  Professor 
Dove  of  Germany.  They 
.all  go  to  prove  that,  in 
these  storms,  the  air  ro- 
tates with  great  velocity, 
around  a  centre  where 
calm  prevails  and  the  bar- 
ometric pressure  is  least. 

Everywhere,  on  opposite 
sides  of  this  centre,  the 
wind  blows  from  opposite 
directions;  while  the 
storm  itself  has  a  rapid 
progressive  motion,  and 
always  advances  from  low- 
er to  higher  latitudes. 

In  the  northern  hemi- 
sphere the  rotary  motion  is 
from  right  to  left,  or  con- 
trary to  that  of  the  hands 
of  a  watch  ;  while  the  pro- 
gressive motion,  within  the 
zone  of  trades,  is  towards 
the  northwest,  and  beyond 
that  zone,  towards  the 
northeast.    (See  Fig.  33.) 

In  the  southern  hemi- 
sphere the  rotary  motion  is 
from  left  to  right ;  the 
progressive,  in  the  zone  of 
trades,  is  towards  the 
southwest,  and  beyond  that  limit,  towards  the  southeast. 

The  progressive  motwn,  therefore,  diverges  slightly  from  the  direc- 
tion of  the  trade-winds  within  their  limits,  and  follows  that  of  the 
return-trades  in  the  zone  of  variable  winds.  Hence  it  would  seem 
to  be  connected  with  the  general  currents  of  the  atmosphere. 

2.  Origin  and  Progress.  The  cyclones  usually  begin  within 
the  tropics,  but  extend  far  into  the  temperate  regions,  where  they 
gradually  spend  their  force.  The  West  India  cyclones,  called  hur- 
ricanes (See  Map  of  Winds,')  generally  originate  in  the  eastern  An- 
tilles, moving  northwestwardly  to  the  coast  of  Florida.  About  the 
limit  of  the  trades,  they  turn  nearly  at  a  right  angle,  and  sweep  over 
the  eastern  coast  of  North  America  and  the  adjacent  waters  of  the 
Atlantic ;  then  crossing  the  ocean,  they  reach  western  Europe,  beyond 
which  they  finally  expire. 


STORM    CARDS. 


REVOLVING  STORMS. 


83 


The  Mauritius  hurricanes  start  in  mid-ocean,  south  of  the  Equator, 
move  southwestward,  sweeping  over  the  islands  of  Mauritius  and 
Reunion,  and  turn  southeastward  at  the  limit  of  the  trades.  The 
typhoons,  originating  in  the  tropical  seas  of  India  and  China,  move 
with  the  monsoons  within  the  zone  of  trades,  turning  northeastward 
beyond  that  zone. 

A  familiarity,  on  the  part  of  navigators,  with  the  Law  of  Storms,  will  enable 
them  to  steer  out  of  the  track  of  a  cyclone;  for  by  observing  the  direction  and 
veering  of  the  wind,  it  can  be  known  into  what  part  of  one  a  vessel  is  entering. 

In  the  northern  hemisphere,  within  the  tropics,  if  the  wind  strikes  a  ship  from 
the  northeast,  and  veers  to  the  north,  the  centre  of  the  cyclone  must  be  to  the 
southeast ;  and  as  the  storm  advances  towards  the  northwest,  a  southwesterly  course 
will  presently  carry  the  vessel  beyond  its  limits.  Within  the  temperate  regions, 
where  the  storm  advances  towards  the  northeast,  the  course  of  the  vessel,  under 
the  same  circumstances,  must  be  towards  the  northwest.  (See  Storm  Cards,  Fig. 
34,  So.) 

In  the  southern  hemisphere  a  northwest  wind,  veering  to  the  north,  shows  the 
centre  of  the  storm  to  be  southwest  of  the  ship.     Her  course,  therefore,  should  be 
to  the  northwest  with- 
in the  tropics,  and  to 
the  northeast  in  the 
temperate  regions. 

3.  Extent  and 
Period.  All 
these  storms  alike, 
cover  only  a  small 
area  at  their  point 
of  origin,  but  their 
violence  is  ex- 
treme. As  they 
advance  their  cir- 
cle gradually  en- 
larges, while  their 
fury  diminishes. 

The  West  India 
hurricane  of  1839 
had,  in  the  Antil- 
les, a  diameter  of 
300  miles,  which 
increased  to  500  at 
the  Bermudas, 
and  800on  the 
parallel  of  50° 
north  latitude. 

Cyclones  occur  most  frequently  soon  after  the  Equinoxes,  at  the 
time  of  the  transition  of  the  seasons  and  the  general  winds.  Accord- 
ing to  Poey,  out  of  365  which  desolated  the  West  Indies  between  the 
years  1493  and  1855,  two-thirds  of  the  whole  number  occurred  be- 
tween August  and  October. 

4.  Aspect.  Except  the  great  volcanic  eruptions  and  earthquakes, 
no  natural  phenomenon  is  more  awe-inspiring  than  these  tremendous 
tempests.  The  portentous  calm,  and  lurid  sky  which  precede  the 
bursting  of  the  storm  ;  the  profound  obscurity  which  follows  the  de- 
scending clouds ;  and  the  extreme  violence  of  the  wind,  —  uprooting 
whole  forests,  overthrowing  the  most  solid  edifices,  sinking  the  larg- 
est ships  in  a  few  moments,  or  uplifting  them  bodily  to  break  them 
on  the  shore,  covering  the  Earth  throughout  its  course  with  ruin  and 
desolation,  —  place  the  cyclones  among  the  long-remembered  events 
whose  recurrence  is  dreaded  by  all. 

5.  Northeasters.  The  great  northeasterly  winter  storms  of 
our  latitudes,  are  but  the  left,  or  western,  half  of  a  revolving  storm. 
Hence  it  is  easy  to  understand  why  the  wind,  though  blowing-  from 


WATEKSPOUTS. 

Observed  in  the  Mediterranean,  near  Sicily,  on  the  27th  of  June,  1827. 


the  northeast,  is  felt  at  Washington  and  Philadelphia  earlier  than 
at  New  York  and  Boston. 

Suppose  the  storm  first  strikes  a  place  with  a  southeast  wind,  as  at  the  point  A 
in  Fig.  34,  in  the  western  half  of  the  storm.  As  it  advances  northeastward,  pass- 
ing over  the  point  A,  on  the  line  A  B,  the  wind  blows  successively  from  the  east, 
northeast,  north,  and  intermediate  points,  finally  reaching  the  northwest  (as  at  B). 
Then  the  storm  ends,  leaving  the  weather  clear  and  cold. 

In  the  eastern  half  of  the  storm  (as  at  C,  Fig.  34),  the  wind  blows  successively 
from  the  southeast,  south,  southwest,  west,  and  intermediate  points,  the  storm  end- 
ing as  before  with  a  northwest  wind.  As  the  storm  advances  from  southwest  to 
northeast,  the  more  southerly  and  westerly  places  are  necessarily  the  first  to  feel 
its  force. 

If  the  centre  of  the  storm  passes  over  a  place,  the  southeast  wind,  which  blows 
continuously  during  the  first  half,  is  followed  by  a  calm,  with  low  barometer.  After 
this  lull  the  northwest  wind  sets  in  abruptly,  and  blows  until  the  storm  is  over. 

III.  Tornadoes  and  Water-Spouts. 

1.   Their   Nature.     Tornadoes  and  water-spouts  repeat  on  a 

small  scale, 
though  with 
scarcely  less  vio- 
1  e  n  c  e  ,  the  phe- 
nomenon of  the 
cyclones. 

When  opposing 
winds  of  different 
temperatures 
meet  in  the  upper 
atmosphere,  a 
whirling  motion  is 
produced,  draw- 
ing down  the  cold 
air  above,  and  a 
vast  amount  of 
vapor  is  condensed 
into  a  thick  black 
cloud. 

Soon,  with  in- 
creasing rapidity 
of  rotation,  the 
whirling  mass 
takes  the  shape  of 
a  vast  funnel,  de- 
scending lower  and  lower  into  the  quiet  atmosphere  beneath,  draw- 
ing up  in  its  vortex  ail  objects  within  its  path.  On  its  track,  vary- 
ing from  a  few  yards  to  a  quarter  of  a  mile  in  width,  trees  are  up- 
rooted, and  houses  unroofed  or  carried  up  into  the  air  by  the  fearful 
power  of  the  tornado. 

When  passing  over  deserts  the  tornado  lifts  up  the  loose  sand  of 
the  surface,  which  it  often  transfers  to  a  distance,  letting  it  fall  as  it 
spends  its  force,  forming  mounds  and  hillocks.  In  this  way  the 
aspect  of  the  surface  of  the  deserts  is  often  materially  changed. 

A  tornado  passing  into  the  sea  forms  a  water-spout.  The  descend- 
ing funnel,  approaching  the  surface  of  the  water,  lifts  up  a  column 
of  spray,  which  joins  in  its  rotary  motion,  thus  binding  together,  as 
it  were,  the  clouds  and  the  sea. 

The  above  illustration,  drawn  from  nature,  represents  a  number 
of  waterspouts,  which  occurred  within  a  short  distance  from  each 
other,  showing  the  various  forms  and  stages  of  this  remarkable  phe- 
nomenon. 

2.  Origin  and  Course.     Tornadoes,  like  cyclones,  usually  move 


— — - — — 


84 


DISTRIBUTION   OF  VAPOR  IN   THE   ATMOSPHERE. 


■with  the  return-trades.  They  seem  to  be  due  to  a  conflict,  in  the 
upper  air,  of  local  currents,  encountering  each  other  in  an  atmosphere 
highly  charged  with  vapors.  A  great  number  originate  over  the  vast 
plains  west  of  the  Mississippi  River,  and  sweep  towards  the  north- 
east, spreading  desolation  along  their  narrow  track. 


ANALYSIS   OF  SECTION   VI. 


I.  Introduction. 


a.  Cause  of  rotary  movement  in  the  air. 

b.  Cyclone.    Definition.     Significance  of  term. 

c.  Accompanying  phenomena. 

d.  Difference  in  cyclones. 

e.  Examples  of  cyclones. 

f.  Position  of  cyclone  regions.    Conclusion  therefrom. 


II. 


Law  of  Storms. 

1.  Motion. 


a.  Character  and  centre. 

b.  Winds  on  opposite  sides  of  centre. 

c.  Cyclones  of  northern  hemisphere. 

d.  Cyclones  of  southern  hemisphere. 

e.  Connection  with  general  winds. 

2.  Origin  and  Progress. 

a.  Latitude  of  beginning. 

b.  Course  of  West  India  hurricanes. 

c.  Course  of  Mauritius  hurricanes. 

d.  Means  of  escaping  from  these  storms. 

3.  Extent  and  Period. 

a.  Area  in  different.parts  of  course.     Example. 

b.  Time  of  most  frequent  occurrence. 

4.  Aspects. 

a.  Impression  created. 

b.  Phenomena  noted. 

5.  Northeasters. 

a.  Character  of  these  storms. 
■  b.  Changes  of  wind. 

IH.  Tornadoes  and  Water  Spouts. 

1.  Their  Nature. 

a.  Resemblance  to  cyclones 

b.  How  produced. 

c.  Form  and  effects. 

e.  Tornado  on  the  desert.     Waterspout*. 

2.  Origin  and  Course. 

a.  Track  of  tornadoes. 

b.  Probable  cause. 

c.  Place  of  origin.    Direction. 


VII.  —  DISTRIBUTION  OF  VAPOR  IN  THE  ATMOS- 
PHERE. 

I.  Humidity  of  the  Air. 

1.  Evaporation.  Water,  whether  in  the  sea  or  on  land,  is 
slowly  transformed  into  invisible  vapor,  which,  being  much  lighter 
than  air  —  as  3 :  5  —  rises,  and  is  diffused  through  every  part  of  the 
atmosphere.  Thus  the  latter  becomes  the  great  reservoir  of  aque- 
ous vapors. 

The  capacity  of  the  air  for  the  absorption  of  vapor  increases  with 
its  temperature ;  but,  at  any  given  temperature,  there  is  a  certain 
limit  beyond  which  it  can  receive  no  more.  When  filled  to  its  ut- 
most capacity  it  is  said  to  be  saturated  with  humidity,  and  the  least 
lowering  of  the  temperature  causes  a  condensation  of  moisture  in  the 
form  of  dew,  fog,  clouds,  or  rain  ;  but  if  the  temperature  is  raised, 
the  capacity  for  vapor  being  increased,  absorption  recommences. 

As  long  as  the  amount  of  vapor  present  in  the  air  is  much  less  than  is  required 
for  saturation,  evaporation  goes  on  rapidly,  and  the  air  continues  to  absorb  the  ris- 
ing vapors.     It  is,  therefore,  called  dry  air. 

When  the  air  is  nearly  saturated,  evaporation  proceeds  but  very  slowly ;  when 
saturation  is  reached,  evaporation  ceases,  and  the  air  is  moist  or  humid. 

From  the  following  table  it  is  evident  that,  by  a  simple  change  of  temperature, 
the  air  may  be  changed  from  moist  to  dry,  or  the  reverse,  without  any  change  in 
the  absolute  amount  of  vapor  it  contains. 


The  weight  of  vapor  contained  in  a  cubic  foot  of  saturated  air,  at  temperatures 
varying  from  20°  to  100°  Fahr.,  ascertained  by  careful  observation,  is  given  in  the 
following  table  :  — 


Temperature  of  Air. 


20°  Fahr. 
32°      " 
50°      " 
62°      " 


Weight  of  vapor  in  a  cubic 
foot  of  saturated  air. 


1.30  grains  Troy, 
2.13       "  " 

4.09       "  " 

6.15       "  " 


Temperature  of  Air. 


70°  Fahr. 
80°      " 
90°      " 
100°      " 


Weight  of  vapor  in  a  cubic 
foot  of  saturated  air. 


8.00  grains  Troy. 
10.95       "  " 

14.81       "  " 

19.79       "  " 


The  relative  humidity  of  the  air  is  the  ratio  which  the  absolute 
amount  of  aqueous  vapor  it  contains,  bears  to  the  amount  required 
for  saturation  at  the  same  temperature.  The  degree  of  moisture 
contained  is  expressed  by  the  fraction  of  saturation. 

If  the  air,  at  the  temperature  of  50°  Fahr.,  contains  but  two  grains  of  vapor  to 
the  cubic  foot  —  one  half  of  that  required  for  saturation  —  its  relative  humidity 
will  be  expressed  by  the  fraction  i,  or  its  equivalent  50  per  cent ;  but  if  the  tem- 
perature be  raised  to  70°  Fahr.,  with  no  addition  of  vapor,  the  air  will  contain  but 
\  of  the  amount  required  for  saturation,  and  its  relative  humidity  will  be  25  per 
cent.  If,  on  the  contrary,  the  temperature  be  lowered,  the  relative  humidity  will 
be  increased  until  saturation  is  finally  reached  and  condensation  begins,  which,  as 
is  shown  by  the  table,  will  not  take  place  until  the  temperature  is  reduced  to  32° 
Fahr. 

2.  Dew  Point.  The  temperature  at  which  saturation  is  com- 
plete, and  the  invisible  vapor  of  the  air  begins  to  condense,  is  called 
the  dew  ■point.  It  is  evident  that,  the  less  the  relative  humidity, 
the  greater  will  be  the  difference  between  the  temperature  of  the  air 
and  the  dew  point.  In  the  above  examples,  the  temperature  of  the 
dew  point  being  32°,  that  difference  is  respectively  18°  and  38°. 

Both  the  relative  and  the  absolute  humidity  of  the  air  may  be  ascertained  by  a 
simple  experiment.  Suppose  the  temperature  of  the  air  to  be  70°  Fahr.,  requir- 
ing, according  to  the  above  table,  8  grains  of  vapor  to  the  cubic  foot,  for  satura- 
tion. Place  the  bulb  of  a  thermometer  in  a  glass  of  water,  gradually  cool  the  lat- 
ter with  ice,  and  note  the  temperature  at  which  moisture  begins  to  appear  on  the 
outer  surface  of  the  glass.  This  is  the  dew  point  of  the  air,  which  we  will  sup- 
pose to  be  50°.  The  number  in  the  table  opposite  this  temperature  shows  the 
absolute  amount  of  vapor  contained  in  the  air,  which  is  4.09  grains  to  the  cubic 
foot.  This  amount  divided  by  8,  the  amount  required  for  saturation,  gives  0.51,  or 
fifty-one  per  cent.,  for  the  degree  of  the  relative  humidity. 

Visible  masses  of  vapor  resting  on,  or  near,  the  ground  are  called 
fogs ;  while  those  floating  in  the  air  at  a  considerable  height  ai-e  dis- 
tinguished as  clouds. 

3.  Forms  of  Clouds.  Clouds  are  classified  according  to  their 
forms,  which  depend  mainly  upon  the  mode  of  formation.  The  prin- 
cipal forms  are  the  cirrus,  feather,  or  curl-cloud ;  the  cumulus,  or 
heaped  cloud ;  the  stratus,  arranged  in  long  horizontal  bands ;  and 
the  nimbus,  a  dense,  formless  cloud,  with  ragged  edges  and  the  bot- 
tom breaking  into  rain-drops.  Several  intermediate  forms  also  occur, 
among  which  the  cirro-cumulus,  or  fleecy  cloud,  is  most  conspicuous. 
(See  illustration,  page  85.) 

The  cirrus  and  cirro-cumulus  clouds  are  the  highest,  are  mostly  in 
the  altitudes  of  perpetual  frost,  and  are  supposed  often  to  consist  of 
minute  ice  crystals.  In  temperate  latitudes  they  are  usually  formed 
in,  and  move  with,  the  upper  air  current,  or  return-trade,  from  the 
tropical  regions. 

The  cumulus  clouds  are  characteristic  of  the  tropics,  and  of  the 
summer  days  in  middle  latitudes,  their  height  depending  upon  the 
relative  humidity  of  the  air.  They  are  formed  by  local  ascending 
currents,  which  carry  a  large  amount  of  vapor  into  the  cooler  upper 
air.  There  the  vapors  are  condensed,  and  are  gradually  heaped  up 
into  these  heavy  masses  of  sharply  defined  clouds,  which  look  like 


DISTRIBUTION   OF   VAPOR   IN   THE   ATMOSPHERE. 


85 


vast  snowy  mountains.     Their  base  is  horizontal,    and  marks  the 
height  at  which  the  dew  point  is  reached  and  condensation  begins. 

The  accumulation  of  vapors  is  often  so  great  that  these  clouds 
form  a  column  several  thousand  feet  high.  In  this  case  the  differ- 
ence in  the  temperature  and  the  electrical  conditions  of  the  upper 
and  lower  portions,  is  such  that  electrical  discharges  take  place,  ac- 
companied by  condensation  of  a  portion  of  the  cloud,  forming  a  thun- 
derstorm.    (See  page  89,  II.,  1.) 

Stratus  clouds  are  most  frequently  seen  in  the  morning  or  eve- 
ning, and  are  always  low.  They  are  formed  by  the  descent  of  the 
higher  clouds  and  vapors  of  midday,  into  the  lower  air,  as  the  tem- 
perature decreases.  They  are  more  frequent  in  winter  and  summer 
than  in  the  intermediate  seasons. 

The  nimbus  cloud  is  more  dense  and  heavy  than  the  others,  which 
may  all  be  transformed  into  the  nimbus  by  a  diminution  of  temper- 
ature.    It  is  of  a  dark  leaden  hue,  changing  into  grey.     This  is  the 
most  common  form  of 
cloud   in   polar  lati- 
tudes ;    and,    during 
the  cold  season,  it  is 
the  most  frequent  of 
the  temperate  zones. 

4.  The  AVERAGE 
HEIGHT  OF  THE 
clouds  is  greatest 
in  the  tropical  lati- 
tudes, and  in  the  sum- 
mer of  the  temper- 
ate ;  and  least  in  the 
polar  regions,  and  in 
the  winter  of  the  tem- 
perate zones. 

As  rain  drops  con- 
stantly increase  in 
size,  by  the  accumu- 
lation of  moisture 
from  the  air  through 
which  they  fall,  it  is 
evident  that  their 
size  will  depend  up- 
on the  height  of  the 
clouds  whence  they  descend,  as  well  as  upon  the  rapidity  of  conden- 
sation. Hence  tropical  rains  and  summer  showers  fall  in  large, 
heavy  drops  ;  while  drizzling  rains,  mists,  and  fogs  are  characteris- 
tic of  cold  latitudes,  and  of  the  cold  season  of  middle  latitudes. 


II.  Condensation. 

1.  Causes  op  Condensation.  Condensation  and  rain  are 
mostly  caused  by  the  cooling  of  currents  of  warm  air  laden  with 
aqueous  vapors. 

A  warm  wind  setting  from  the  tropics  clear  and  dry,  and  ad- 
vancing into  cooler  latitudes,  continually  diminishes  in  temperature. 
Hence,  without  receiving  additional  vapors,  its  relative  humidity 
constantly  increases  until  saturation  is  reached,  when  the  air  be- 
comes moist  and  cloudy,  and  finally  rain  falls. 

A  cold  wind,  on  the  contrary,  starting  from  the  polar  regions  sat- 
urated with  vapor  and  full  of  clouds,  and  advancing  to  warmer 
latitudes,  has  its  capacity  for  moisture  constantly  increased.     Hence 


•  STRATUS.       W  CIRRUS.        <?v-   CUMULUS.      v  ?*  CIRRO-CUMULUS. 


FORMS   OF   CLOUDS. 


it  becomes  at  every  step  less  humid,  and  its  clouds  dissolve,  leaving 
the  air  clear  and  dry.  Our  northwesterly  windc,  and  the  Etesian 
winds,  which  bear  the  vapors  of  the  Mediterranean  into  the  Sahara, 
are  examples  of  this  change. 

Thus  warm  winds,  blowing  towards  cooler  regions,  bring  rain  ; 
while  cold  winds,  advancing  to  warm  climates,  bring  fair  weather  and 
drought.  When  the  two  are  intermingled,  the  temperature  of  the 
former  is  reduced,  and  cloudiness  or  rain  is  the  result. 

Ascending  currents  give  rise  to  similar  phenomena'.  The  warm 
air,  laden  with  vapors  exhaled  from  the  heated  surface  of  land  or 
sea,  rising  into  the  upper  regions  of  the  atmosphere,  expands  and 
becomes  cool ;  and  its  vapors,  condensing  rapidly,  return  to  the 
ground  in  copious  showers.  Thus  are  produced  the  rains  of  inter- 
tropical regions,  and  the  summer  showers  of  middle  latitudes. 

2.  Influence  of  Relief  and  Surface.  Mountain  chains,  in 
general,  act  as  condensers,  especially  when  lying  across  the  path  of 

warm  winds.  Upon 
the  side  exposed  to 
the  wind,  the  air  is 
forced  upward  along 
the  slopes,  and  its  va- 
pors are  condensed 
into  clouds,  whence 
torrents  of  rain  fall ; 
while  on  the  opposite 
side  it  descends,  with 
increasing  tempera- 
ture, as  a  dry 
wind. 

Thus  the  Andes  Moun- 
tains,  intercepting  the 
vapors  borne  by  the 
southeast  trades  of 
South  America,  separate 
the  moist  plains  and 
luxuriant  forests  of  the 
Amazon  and  Paraguay 
basins,  from  the  rainless 
and  barren  coasts  of 
Peru  and  Bolivia.  The 
Sierra  Nevada,  in  Cali- 
fornia, and  the  Cascade 
Range,  in  Oregon,  lying 
across  the  path  of  the  warm  return  trades,  separate  well  watered  and  fruitful  coast 
regions  from  a  dry  and  barren  interior. 

The  Scandinavian  Mountains,  in  Europe,  rob  the  southwest  return-trade  of  its 
vapors,  so  that,  though  it  brings  rain  in  Norway,  it  is  the  fair  weather  wind  in 
Sweden.  On  the  southern  slopes  of  the  Alps  from  60  to  90  inches  of  rain  fall 
annually,  varying  with  the  locality,  while  the  northern  slope  receives  but  35 
inches.  The  Himalaya  Mountains  and  the  Western  Ghauts,  in  India,  interpose 
a  like  barrier  to  the  vapors  borne  by  the  southwest  monsoons,  and  occasion  simi- 
lar contrasts  in  the  rain-fall  upon  their  opposite  slopes. 

Plateaus  usually  receive  less  rain  than  other  forms  of  relief ,  be- 
cause the  mountains,  which  form  the  borders  of  the  greater  number, 
prevent  the  vapors  borne  by  the  wind  from  reaching  them.  Again, 
the  air  resting  upon  these  broad  elevated  surfaces,  which  absorb  the 
powerful  rays  of  the  Sun  (page  72,  II.,  2),  is,  in  summer,  warmer 
than  the  surrounding  atmosphere  ;  hence  it  tends  to  dissolve,  rather 
than  to  condense,  the  vapors  borne  into  it  by  lateral  currents. 

The  nature  and  covering  of  the  soil  also  has  an  influence  upon  the 
condensation  of  the  vapor  in  the  air.  A  barren  region,  with  noth- 
ing to  shield  it  from  the  burning  rays  of  the  sun,  becomes  intensely 
heated  ;  and  imparts  to  the  superincumbent  air  so  high  a  tempera- 


*^Y 


180        Longitude     160     West     iVoin     140     Greenwiih.     120 


Decrease  of  Rain  toward  the  interior  of  the  Land  &  increase  in  the  Mountain  Regions 


.Alleghany  M'.* 


Washington 


AJl. 


Andes 


Limn 


SOUTH  AMERICA 

Plateau     of     Brazil 

recis  M*? 


Explanation 

HB    Great   amount  of  Rain 

1— ■■  J    Lesser  amount    of  Rain. 

Rainless  Ih'strict 


Becife  (  PerxiambucoJ 


X-Saruioz  &  tT.ITrumholjs  d*l . 


Showing  the  ] 

OVER    T 


Polar  limits  of  the  various 
Regions   of  Rairx 

In  the  profiles  ihr  blue  ni 

l-O  20  0 


Entered,  according  to  Act  of  Congress,  in  the  year ISftZ.'by  Scrabnev  A 


uijjt  Sc  C0..1V1  tht  ''(Tier  of* the  Librarian,  of  Congress, at  Wasiimgton.  C.T- . 


WSpeller  sculp- 


88 


DISTRIBUTION   OF  VAPOR  IN   THE   ATMOSPHERE. 


ture  as  to  dissipate  all  clouds  which  may  float  into  it  from  the  sur- 
rounding atmosphere.  A  covering  of  vegetation,  on  the  contrary, 
shields  the  soil  from  the  sun's  rays,  keeps  its  temperature  lower,  and 
promotes  condensation. 

Hence  forests  receive  more  rain  than  treeless  regions  similarly  sit- 
uated, while  at  the  same  time  they 
check  the  evaporation  of  moisture 
from  the  soil,  and  favor  the  gradual 
percolation  of  the  rain-water 
through  the  ground;  thus  they 
equalize  the  irrigation  of  the  sur- 
rounding country,  and  augment  the 
volume  of  its  springs  and  rivers. 


NORTH    POLE 


III.    Distribution 
Rain. 


of  Clouds  tun! 


1.  Laws  of  Distbibution. 
Though  the  distribution  of  rain  is 
much  more  liable  than  the  temper- 
ature, to  irregularities  and  ex- 
tremes, dependent  upon  local  cir- 
cumstances, yet  the  following  gen- 
eral laws  hold  good :  — 

(1.)  The  average  quantity  of  rain 
falling  annually  is  greatest  in  the 
tropical  regions,  where  the  rapidity 
of  evaporation,  and  the  absolute 
amount  of  vapor  in  the  air,  are 
both  extreme  ;  and  the  average  decreases  gradually  with  increasing 
latitude. 

The  following  table,  showing,  approximately,  the  average  annual  rainfall  of  dif- 
ferent latitudes,  exhibits  clearly  the  above  law  : 


South    pole 
fig.  36.    comparative  cloudiness  in  the  different  latitudes, 


Latitude. 

Inches  of  Rain. 

Latitude. 

Inches  of  Rain. 

0°  (Equator.) 

100 

50° 

30 

20° 

80 

60° 

20 

30° 

60 

70° 

10 

40° 

40 

80° 

5 

(2.)  The  cloudiness  of  the  air  and  the  number  of  rainy  days  in  the 
year,  increase  gradually  from  ec^^eal  to  polar  regions.     (Fig.  36.) 

Within  the  tropics,  the  averag*Pamber  of  cloudy  or  rainy  days 
in  the  year  is  only  from  eighty  to  ninety,  and  often  much  less.  In 
the  middle  latitudes  there  are  twice  this  number  ;  and  in  the  polar 
regions  fogs  and  clouds  reign  supreme,  except  during  the  winter. 

(3.)  Both,  the  average  rainfall  and  the  number  of  cloudy  or  rainy 
days,  diminish  gradually  from  the  coasts  to  the  interior  of  the  conti- 
nents. 

The  following  table  shows  the  variation  in  rainfall  and  rainy  days,  in  coun- 
tries of  the  Old  World,  between  45°  and  50°  north  latitude.  (See  diagram  in 
Map  of  Rains.) 


Countries. 

Average 
RainfaU. 

Rainy  Days . 

Countries. 

Average 
Rainfall. 

Rainy  Days. 

British  Isles      .     . 
Western  France    . 
Eastern  France     . 
Germany,  Cen.  &  N. 

32  inches. 
25       " 
22       " 
20       " 

156 
152 
147 
150 

Hungary      .     .     . 
Russia,  (Kasan)  . 
Siberia,  (Yakutsk) 

1 7  inches. 
14       " 
10       " 

Ill 
90 
60 

Observations  in  North  America  show  a  like  diminution  with  increasing  distance 
from  the  sea ;  but,  on  account  of  the  free  entrance  of  vapors  from  the  Gulf  of 
Mexico  into  the  interior  of  the  continent,  the  decrease,  from  the  Atlantic  west- 
ward, as  far  as  the  Mississippi,  is  less  marked. 

The  moisture  from  the  Mediterranean  and  the  Indian  Ocean,  on  the  contrary, 
is  intercepted  by  the  mountain  ranges  composing  the  main  axis  of  Asia-Europe, 

which  form  a  great  barrier  near  the  south- 
ern shores.  This  fact,  with  the  plateau 
character  of  Iran  and  Mongolia,  accounts 
for  the  lack  of  moisture  which  dooms  these 
countries  mainly  to  the  condition  of  a 
desert. 

(By  turning  to  the  Map  of  Rains  it 
will  be  seen  that  the  great  central  zone  of 
deserts,  extending  from  the  Atlantic  — 
through  the  Sahara,  Arabia,  Iran,  and 
Mongolia  —  nearly  to  the  Pacific,  lies  in 
the  interior  of  the  greatest  continental 
masses  of  the  Old  World.) 

2.  Rainfall  of  New  and 
Old  Wobld.  The  New  World, 
which  forms  a  comparatively  nar- 
row belt  of  land  between  two  great 
oceans,  receives,  both  in  temperate 
and  tropical  regions,  a  larger  aver- 
age amount  of  rain  than  the  Old 
World. 

The  average  for  the  tropical  re- 
gions of  the  New  World  is  roughly 
estimated  at  115  inches;  while  that 
of  the  Old,  with  its  large  and  com- 
pact masses  of  land,  is  but  77,  mak- 
ing the  mean  for  the  entire  zone  96  inches.  The  average  of  tem- 
perate America  is  38  inches ;  that  of  Asia-Europe,  in  temperate  lat- 
itudes, is  34 ;  making  a  mean  of  36  for  the  entire  zone.  Eastern 
North  America  has  an  average  of  40  inches  of  rain  for  25  in  western 
Europe,  in  corresponding  temperatures. 

ANALYSIS  OF   SECTION   VH. 

I.  Humidity  of  the  Air. 

1.  Evaporation. 

a.  Process.     Reservoir  of  vapors. 

b.  Capacity  of  air  for  absorbing  vapor.    Saturation. 

c.  Dry  air.     Moist  air.     Change  from  one  to  the  other. 

d.  Saturation  at  different  temperatures. 

e.  Relative  humidity  of  air  how  expressed. 

f.  Changes  of  relative  humidity. 

2.  Dew  Point. 

a.  Definition. 

b.  Relation  to  relative  humidity  of  air. 

c.  Humidity  of  the  air  ascertained  how 
8.  Forms  of  Clouds. 

a.  Classification. 

b.  Cirrus  and  cirro-cumulus  clouds. 

c.  Cumulus. 

d.  Stratus. 

e.  Nimbus. 

4.  Average  Height  of  Clouds. 

a.  Where  and  when  greatest. 

b.  Where  and  when  least. 

c.  Effect  on  size  of  rain  drops. 

d.  Effect  on  character  of  rains. 

II.  Condensation. 

1.  Causes. 

a.  Condensation  usually  due  to  what. 

b.  Effect  of  passage  of  warm  winds  to  cold  regions 

c.  Effect  of  passage  of  cold  winds  to  warm  regions. 

d.  Effect  of  intermingling  of  warm  and  cold  winds 

e.  Condensation  by  ascending  currents. 

2.  Influence  of  Relief  and  Surface. 

a.  Condensation  by  mountain  chains.    Examples 

b.  Condensation  on  plateaus. 

c.  Influence  of  barren  soil. 

d.  Influence  of  forests. 

IH.  Distribution  of  Clouds  and  Rain. 

1.  Laws  of  Distribution. 

a.  Of  annual  average  rainfall. 

b.  Of  cloudiness  and  rainy  days. 

c.  Variation  from  coasts  to  interior 

2.  Rainfall  of  New,  and  of  Old  World. 

a.  Average  in  tropical  regions. 

b.  Average  in  temperate  regions. 


RAIN    IN   DIFFERENT  LATITUDES. 


89 


VIII. —  RAIN   IN   DIFFERENT   LATITUDES. 


I.  Rain  Zones. 

Owing  to  the  intimate  relation  which  exists  between  the  temper- 
ature, the  winds,  and  the  condensation  of  vapors,  each  of  the  great 
climatic  zones  of  temperature  and  winds  has  also  a  distinct  system 
of  rains. 

Within  the  tropical  regions,  which  are  characterized  by  uniform 
temperature,  and  trade  winds  or  calms,  the  rains  are  occasioned  by 
ascending  currents,  formed  in  the  hottest  part  of  the  day  or  year. 
Hence  the  trade  zones  are  zones  of  periodical  rains. 

In  the  temperate  and  cold  regions  the  rains  are  mainly  caused  by 
the  intermingling  of  cold  and  warm  horizontal  currents.  This  may 
occur  at  any  time,  but  is  most  frequent  in  winter,  spring,  and  au- 
tumn ;  consequently  in  these  zones  the  rains  are  either  perennial  or 


only  partially  periodical. 

II.    Rains  of  Tropical  Re- 
gions. 

1.  In  the  Belt  of  Equa- 
torial Calms,  where  there 
is  a  constant  ascending  cur- 
rent which  reaches  its  great- 
est velocity  and  humidity  in 
the  hottest  part  of  the  day, 
there  are  nearly  daily  rains, 
occurring  during  the  hours 
of  greatest  heat.    (Fig.  37.) 

In  the  morning  the  sky  is  clear, 
but  towards  noon  masses  of  white 
cumulus  clouds  appear  at  different 
points,  rapidly  spreading  and  dark- 
ening, until  the  whole  heaven  is 
overcast,  when  the  storm  bursts. 
Vivid  flashes  of  lightning  traverse 
the  blackened  sky,  accompanied 
by  deafening  thunder,  and  the 
rain  falls  in  torrents  for  two  or 
three  hours.  Then  it  ceases ;  the 
ascending  current  slackens ;  the 
remaining  clouds,  as  they  descend 


hobth    POie 


Position 

of  the  S 
Oune  21s 


south   pot* 

PIG.    37.      DISTRIBUTION  OF    RAIN   IN  THE   DIFFERENT    LATITUDES 

by  their  weight  into  the  warmer  air,  are  dissolved  ;  and  the  night  is  cloudless. 

2.  Within  the  Belts  of  Trades  all  the  rain  of  the  year  falls 
in  the  few  months  during  which  the  Sun  is  not  far  from  the  zenith, 


that  is  in  the  summer,  when  the  heat  is  so  great  that  ascending  cur- 
rents take  the  place  of  the  trades.  This  period  is  called  the  rainy 
season;  the  remainder  of  the  year,  the  dry  season.  (See  Fig.  37.) 
(1.)  Dry  Season.  While  the  trades  blow  without  interruption, 
though  abundant  vapors  may  fill  the  air,  there  is  nothing  to  cause 
condensation,  except  the  cooling  of  the  air  during  the  night,  when 
copious  dews  are  deposited.  Hence  the  sky  preserves  a  constant 
serenity  and  a  deep  azure  tint ;  and  the  atmosphere  is  cloudless,  es- 
pecially when  the  Sun  is  in  the  opposite  hemisphere. 

(2.)  Rainy  Season.  As  the  Sun  approaches  the  zenith  the  trades 
become  irregular,  being  replaced  by  calms  and  fitful  breezes  from 
any  direction.  The  sky  assumes  a  whitish  tint ;  clouds  appear  near 
the  horizon,  and  vanish,  as  if  driven  by  a  swift  wind  ;  finally  they 
gather  in  the  zenith,  about  midday,  and  burst  in  sudden  showers 
and  terrific  thunder-storms,  like  those  of  the  zone  of  equatorial 
calms.  The  air  is,  at  all  times,  nearly  saturated  with  moisture. 
As  the  altitude  of  the  Sun  increases,  the  showers  become  more 

frequent  and  prolonged,  last- 
ing, sometimes,  the  whole 
day  ;  and  floods  of  rain  de- 
scend, filling  the  streams 
and  inundating  vast  areas  of 
country.  As  many  as  twen- 
ty-one inches  of  rain  have 
been  known  to  fall  at  Cay- 
enne, in  South  America,  in 
a  single  day. 

After  the  Sun  has  passed 
the  zenith,  the  rains  grad- 
ually diminish  in  amount 
and  frequency ;  and  when 
the  trade  wind  resumes  its 
sway,  they  cease  entirely. 

Near  the  Equator  the  rainy  sea- 
son consists  of  two  parts,  sepa- 
rated by  a  brief  period  of  fair 
weather.  The  first  rains  take 
place  when  the  Sun  is  passing  the 
zenith  towards  the  adjacent  tropic, 
and  the  second  on  his  return  from 
it.  Near  the  tropics  the  two  pe- 
riods are  blended  into  one. 


of  the  Sun 


3.  Exceptional  Regions.  (1.)  The  eastern  coasts  of  the  pe- 
ninsula of  Deccan,  in  India,  receive  rain  when  the  Sun  is  in  the 
southern  hemisphere,  that  is,  during  the  northern  winter. 


QUESTIONS  ON  THE  MAP  OF  RAINS. 


Explain  the  coloring  of  the  map.  What  do  the  large  figures  in  the  margins  indicate? 
What  do  the  figures  accompanying  the  names  indicate  ?  (See  explanation  at  the  bottom  of  the 
map.)  What  does  the  upper  diagram  on  the  right  hand,  at  the  bottom  of  the  map,  indicate? 
What  is  shown  by  the  lower  diagram  ?     What  do  the  two  diagrams  at  the  left  show? 

In  what  seasons  of  the  year  does  condensation  taks  place  in  the  Arctic  regions  ?  Into  what 
form  are  the  vapors  condensed  ?  What  is  the  average  rainfall  of  the  Arctic  regions  ?  When 
does  condensation  take  place  in  the  regions  next  south  of  the  Arctic?  Into  what  form  are  the 
vapors  condensed  in  winter?  What  is  the  average  rainfall  in  the  northern,  the  central,  and 
the  southern  portions  of  this  zone? 

How  does  the  amount  of  rain  falling  annually  vary  from  the  British  Isles  to  Siberia?  (See 
diagram,  and  figures  near  Dublin  and  Barnaul.)  When  do  the  rains  fall  in  the  region  of  seini- 
pcriodical  rains?  Trace,  naming  the  cities  near  it,  the  northern  equatorial  limit  of  the  fall  of 
snow  at  the  sea  level.     Trace  the  limit  of  snow  at  the  sea  level  in  the  southern  hemisphere. 

What  is  the  average  rainfall  at  Astrakhan,  on  the  Caspian?  At  Ofen,  on  the  Danube?  At 
Paris  ?  At  Cherbourg,  on  the  coast  of  France  ?  Why  docs  more  rain  fall  on  the  west  coast  of 
Europe  than  iu  the  interior?  What  two  places  on  this  coast  have  a  larger  amount  of  rain  than 
any  other  place  in  western  Europe  ?  What  two  are  next  in  amount  ?  How  does  the  rainfall 
vary,  from  east  to  west,  in  the  United  States,  in  the  latitude  of  Cambridge? 


Where  are  the  regions  of  periodical  rains  situated?  How  do  the  seasons  differ  in  these  re- 
gions? When  do  rains  fall  in  the  immediate  vicinity  of  the  equator?  In  what  portions  of  the 
globe  is  the  average  rainfall  greatest?  At  what  two  places  is  the  greatest  known  amount  of 
rain  ?  What  winds  bring  rain  at  these  places  ?  Where  is  the  largest  observed  amount  of  rain 
in  South  America? 

In  what  portions  of  North  America  does  most  rain  fall  ?  What  winds  bring  most  rain  there  ? 
What  are  the  dryest  regions  in  the  southern  half  of  North  America?  (See  page  91,  Topic  I., 
2.)  How  does  the  rainfall  on  the  Sierra  Nevada  and  Rocky  Mountains  compare  in  amount 
with  that  of  the  plateau?     Why?     (See  page  85,  Topic  II.,  2.) 

How  does  the  interior  of  the  plateau  of  Brazil  compare  in  amount  of  rain  with  the  eastern 
part?  What  is  the  cause  of  the  absence  of  rain  west  of  the  Andes,  in  the  same  latitude? 
(See  page  90,  Topic  I.,  1.)  What  winds  bring  rain  to  the  southern  half  of  South  America? 
How  do  the  eastern  and  western  portions  of  this  region  compare  in  the  amount  of  rain  ?  W  hy 
is  this?  What  are  the  dryest  parts  of  the  Old  World?  How  do  you  explain  the  lack  of  rain 
in  northern  Africa  and  Arabia?  (See  page  90,  Sub-tropical  Bell.)  How  do  you  account  for 
the  small  amount  of  rain  in  the  interior  of  eastern  Asia  and  Iran?  (See  page  88,  Topic  HI. 
(3).)     What  parts  of  Australia  have  most  rain?     Why  is  the  interior  dry? 


90 


RAIN   IN  THE   SOUTHERN  CONTINENTS. 


The  southwest  monsoon,  which  blows  during  the  summer  (See 
page  78,  Top.  1. 1),  and  brings  copious  showers  to  the  western  coasts, 
reaches  the  eastern  only  after  its  passage  over  the  Western  Ghauts 
and  the  plateau  of  Deccan ;  hence  it  brings  drought. 

The  northeast  monsoon,  blowing  when  the  Sun  is  in  the  southern 
hemisphere,  carries  to  the  eastern  coast  abundant  vapors  from  the 
Gulf  of  Bengal.  These,  condensed  upon  the  slopes  of  the  eastern 
Ghauts,  give  copious  showers,  while  the  western  coast  has  its  dry 
season. 

(2.)  Sub-tropical  Belt.  Immediately  beyond  the  tropics,  on  the 
margin  of  the  trade-wind  zones,  between  the  parallels  of  24°  and 
28°,  less  rain  generally  falls  than  in  the  neighboring  latitudes ;  and 
there  exists,  as  it  were,  an  intermediate,  dry  zone.  (See  Fig.  37.) 
Situated  somewhat  beyond  the  region  of  tropical  summer  rains,  it 
receives  but  little  water  from  that  source ;  and  it  lies  too  near  the 
tropics  to  have  the  benefit  of  the  winter  rains,  which  are  brought  to 
the  latitudes  beyond  by  the  descending  return-trades. 

The  Sahara,  the  deserts  of  Arabia  and  Northern  India,  and  the  arid  plateaus 
of  Mexico  and  Lower  California,  all  include  the  sub-tropical  belt  of  the  northern 
hemisphere ;  while  the  Desert  of  Atacama  in  South  America,  and  of  Kalahari  in 
Africa,  together  with  the  barren  wastes  of  Central  Australia,  occupy  a  corre- 
sponding position  in  the  southern  hemisphere. 

The  sub-tropical  position  of  these  regions,  by  diminishing  their  share  of  rain, 
while  it  increases  the  summer  heat,  deprives  the  soil  of  a  covering  of  vegetation, 
and  this  barrenness  (see  page  85,  Topic  II.,  2)  intensifies  both  heat  and  drought. 
Thus  deserts  perpetuate  themselves,  whereas  artificial  irrigation  has  redeemed 
many  regions  naturally  sterile;  and  by  clothing  the  soil  with  vegetation,  has 
greatly  ameliorated  their  climate. 


III.  Rains  or  Temperate  Regions. 

1.  Semi-Periodical  Rains.  (1.)  Belt  of  Winter  Rains.  In 
the  warm-temperate  zone,  extending  from  latitude  28°  to  about  35°, 
where  the  trades  prevail  in  summer  and  variable  winds  in  winter, 
the  latter  is  the  rainy  season.  The  winter  rains  are  occasioned  by 
the  intermingling  of  the  cold  polar  current  with  the  vapor-laden  re- 
turn-trades, which,  in  these  latitudes,  descend  into  the  lower  air  in 
winter,  when  the  sun  is  in  the  opposite  hemisphere. 

In  other  seasons,  the  return-trades  being  above  and  the  polar  winds 
below,  the  two  do  not  intermingle  sufficiently  to  cause  any  consider- 
able condensation  of  vapors  ;  and  the  presence  of  the  warm  air  at  a 
comparatively  slight  elevation,  prevents  condensation  by  ascending 
currents  during  the  heat  of  summer.  Hence  little  or  no  rain  falls 
except  in  winter,  and  the  long  summers  are  rainless. 

Thus  the  warm-temperate  zone  is  characterized  by  a  periodicity 
of  rains  scarcely  less  marked  than  that  of  the  torrid  zone,  though 
the  rain  falls  during  the  opposite  season  of  the  year. 

On  the  Pacific  coast  of  North  America,  this  belt  extends  several  degrees  further 
from  the  Equator  than  elsewhere.  In  California,  as  far  as  40°  north  latitude, 
the  rain  falls  almost  exclusively  in  winter.  The  free  sweep  of  the  returning  trade 
winds  of  the  Pacific  Ocean,  and  the  mighty  barrier  which  the  Rocky  Mountains 
oppose  to  the  polar  winds,  may  perhaps  account  for  this  apparent  irregularity. 

(2.)  Belt  of  Equinoctial  Rains.  The  Sun  having  advanced  to 
the  Equator,  the  return-trades  descend  into  the  lower  air,  between 
the  parallels  of  35°  and  42°.  In  these  latitudes  the  winter  rains 
diminish,  the  spring  and  autumnal  rains  show  a  maximum,  and  the 
summers  are  no  longer  entirely  dry.  They  form,  therefore,  a  tran- 
sition between  the  belt  of  almost  periodical  winter  rains,  and  that  of 
the  perennial  rains. 

In  the  eastern  half  of  the  United  Stales,  the  southwesterly  winds,  which  prevail  in 
the  summer,  spread  over  the  interior  and  the  Atlantic  plains  an  abundant  supply 
of  vapors  from  the  warm  waters  of  the  Gulf.     Frequent  copious  showers  refresh 


the  soil  during  the  months  of  greatest  heat,  which  show  a  maximum  of  rain. 
Thus  the  dry  summers  of  the  warm- temperate  region  disappear,  and  with  them 
the  periodical  character  of  the  rains,  so  well  marked  elsewhere  in  this  belt. 

3.  Belt  of  Perennial  Rains.  In  the  cool-temperate  latitudes, 
where  the  warm  and  the  cold  surface  winds  alternate  in  all  seasons, 
condensation,  producing  rain  or  snow,  occurs  in  all  parts  of  the  year. 
Still  it  is  most  abundant  in  summer,  when  the  warm  return-trades 
extend  farthest  north ;  and  least  in  winter,  especially  in  the  interior 
of  the  continents,  where  the  polar  currents  prevail  to  a  great  extent. 

IV.  Rains  of  Polar  Regions. 

Within  the  polar  regions,  where  southerly  winds  blow  to  a  cer- 
tain extent  in  summer,  that  season  is  marked  by  almost  continual 
cloudiness  and  fog.  The  clouds  are  low,  and  fine  drizzling  rains  are 
of  frequent  occurrence,  with  snow  in  spring  and  autumn.  The  win- 
ters, however,  are  dry  and  clear,  and  their  long  nights  cloudless. 


ANALYSIS   OP   SECTION   VIII. 


I.  Rain  Zones. 


a.  Cause  and  character  of  tropical  raius. 

b.  Cause  and  character  of  rains  in  middle  and  cold  zones. 


II.  Rains  In  Tropical  Regions. 

1.  Ik  BUT  op  Calks. 

a.  Time  and  cause  of  rains. 

b.  Description  of  rain-storm. 

2.  Ik  Belt  of  Trades. 

a.  Distinction  of  seasons. 

b.  Cause  and  character  of  dry  season. 

c.  Character  of  rainy  season. 

Beginning.    Height.    Close. 
Division  of  rainy  season  near  equator. 

3.  Exceptional  Regions. 

a.  Rains  on  east  coast  of  India. 

b.  Sub-tropical  rains. 

Quantity.    Cause  of  scarcity.    Consequences. 

III.  Rains  of  Temperate  Regions. 

1.  Belt  op  Winter  Rains. 

a.  Location. 

b.  Cause  of  winter  rains. 

c.  Conditions  in  other  seasons. 

d.  Comparative  periodicity. 

e.  Exceptional  extent  on  Pacific  coast. 

2.  Belt  of  Equinoctial  Rains. 

a.  Location. 

b.  Time  of  rainfall. 

c.  Exception  in  eastern  half  of  Uuited  States. 

3.  Belt  of  Perennial  Rains. 

a.  Location. 

b.  Character  of  winds  and  rains. 

c.  Maximum  and  Minimum. 

IV.  Rains  of  Polar  Regions. 

a.  Conditions  in  summer. 

b.  Conditions  in  winter. 


IX.  — RAIN  IN  THE  SOUTHERN   CONTINENTS. 


I.  South  America. 

1.  Intek-tropical  Region.  South  America,  of  all  the  conti- 
nents, is  the  most  abundantly  provided  with  moisture.  The  north- 
ern and  broadest  part  lies  in  the  regions  of  daily  and  of  peri- 
odical rains,  and  at  the  west  of  the  Atlantic  Ocean,  whose  plentiful 
vapors  are  carried  into  it  by  the  trade  winds.  The  interior  of  the 
plateau  of  Brazil,  however,  has  less  copious  rains,  the  vapors  of  the 
ocean  being  partially  intercepted  by  the  mountains  adjacent  to  the 
coast. 

In  the  region  of  the  equatorial  calms,  copious  rain  falls  west  of 
the  Ancles,  as  well  as  on  the  eastern  slope  ;  but  in  the  belt  of  south- 


RAIN   IN  THE  NORTHERN   CONTINENTS. 


91 


ern  trades  no  rain  falls  on  the  western  slope,  the  vapors  carried  by 
the  east  winds  being  condensed  in  the  passage  of  the  latter  over  the 
mountains.  From  Punta  Parina  to  20°  south  latitude,  the  coast  is 
bathed  with  vapors  from  the  adjacent  seas,  which,  condensed  into 
winter  fogs  by  the  cold  Peruvian  current,  are  wafted  to  the  lands  by 
the  southerly  monsoons.  Hence,  though  rainless,  it  is  not  entirely 
sterile,  on  account  of  the  moisture  in  the  air. 

2.  Beyond  the  tropics,  in  the  regions  of  semi-periodical  and 
perennial  rains,  the  return-trades  which  come  from  the  northwest, 
and  the  other  westerly  winds,  strike  the  Pacific  coast,  but  part  with 
their  vapors  in  crossing  the  Andes.  On  the  western  slope,  Chili  has 
only  moderate  winter  rains  ;  but  from  Valdivia  to  Cape  Horn,  clouds 
and  rain  prevail  all  the  year  round,  and  the  average  rainfall  is  fully 
as  great  as  within  the  tropics. 

The  eastern  or  main  slope  is  comparatively  dry,  especially  in  the 
higher  portions  near  the  mountains  ;  but  occasional  northeasterly 
winds,  bringing  showers,  and  thunder-storms  from  the  south  during 
the  summer,  redeem  this  part  of  the  continent  from  complete  aridity. 

Paraguay,  southern  Brazil,  and  the  states  west  of  the  La  Plata, 
have  the  winter  and  equinoctial  rains  of  these  latitudes,  coming  from 
the  north  and  northeast ;  but  the  Pampas  of  Buenos  Ayres  are  lia- 
ble to  long  and  frequent  droughts,  and  the  dryness  of  the  Patagonian 
plains  is  in  great  contrast  with  the  excess  of  moisture  on  the  oppo- 
site side  of  the   Andes. 

II.  Africa. 

1.  Central  Region.  Africa  has,  like  South  America,  copious 
rains  in  the  zone  of  calms,  and  in  the  zones  of  periodical  rains,  as  far 
as  16°  north  latitude  and  20°  south.  No  high  and  continuous  moun- 
tain ranges  shut  out  the  moisture  brought  by  the  monsoons,  both 
from  the  Indian  and  the  Atlantic  Ocean  (see  Map  of  Winds)  ; 
though  the  marginal  swells  partially  intercept  the  vapors,  giving  to 
the  coasts  more  abundant  rains  than  to  the  interior. 

2.  Northern  Africa.  "With  the  exception  of  the  Mediterranean 
shores,  a  narrow  belt  along  the  Atlantic  coast,  and  some  groups  of 
mountains  in  the  interior,  North  Africa,  beyond  latitude  16°,  is 
almost  absolutely  rainless.  These  exceptional  regions  receive  the 
winter  and  spring  rains  of  the  extra-tropical  zone. 

The  rainless  region  forms  the  Sahara,  the  largest  desert  upon  the 
globe.  Its  aridity  is  occasioned  by  the  position  of  a  great  portion 
of  its  area  in  the  subtropical  zone ;  its  situation  at  the  southwest  of 
the  great  continent  of  Asia,  which  causes  the  prevailing  northeast- 
erly winds  of  its  latitude  to  come  from  arid  lands ;  the  elevation  of 
the  plateaus  of  Arabia  and  Abyssinia,  which  exclude  from  it  the 
winds  from  the  northern  part  of  the  Indian  Ocean  ;  and  the  nature 
of  its  surface,  which  is  such  as  to  be  most  unfavorable  to  condensa- 
tion.    (See  page  85,  Topic  II.,  2.) 

3.  Southern  Africa.  A  portion  of  the  continent  beyond  the 
parallel  of  20°  south  latitude,  is  also  in  the  sub-tropical  zone,  and  has 
its  desert,  that  of  Kalahari,  under  the  Tropic  of  Capricorn  ;  but  its 
less  extent,  and  its  exposure  to  the  winds  from  the  surrounding  seas, 
redeem  it  from  the  complete  drought  belonging  to  the  Sahara.  The 
two  arid  regions,  embracing  so  large  a  portion  of  its  area,  give 
Africa  its  especial  character,  rendering  it  the  hottest  of  all  the  con- 
tinents, and  the  dryest  in  the  tropical  regions. 

III.  Australia. 

Australia,  regarded  as  a  whole,  is  somewhat  scantily  sup- 
plied with  rain  ;  but,  as  in  southern  Africa,  the  small  area  of  the 


continent,  its  position  in  the  midst  of  the  sea,  and  the  absence 
of  barriers  excluding  the  sea  winds,  all  tend  to  diminish  the  dryness 
of  its  sub-tropical  belt.  The  northern  portion  receives  the  periodi- 
cal summer  rains  of  inter-tropical  regions,  and  the  southern  the 
semi-periodical,  or  spring  and  winter  rains. 

ANALYSIS  OF   SECTION  IX. 

I.  South  America. 

1.  Inter-tropical  Region. 

a.  Comparative  abundance  of  moisture. 

b.  Rains  west  of  the  Andes  in  the  belt  of  calms. 

In  the  trade  belt. 

2.  Rains  Beyond  the  Tropic. 

a.  On  western  slope. 

b.  On  eastern  slope. 

II.  Africa. 

1.  Central  Region. 

2.  Northern  Africa. 

a.  General  character  in  regard  to  moisture. 

b.  Rainless  region. 

3.  Rains  m  Sooth  Africa.    General  character  of  Afric*. 

III.  Australia. 

a.  General  character. 

b.  Rain  in  the  different  portions. 

X.  — RAINFALL   OF   THE    NORTHERN   CONTINENTS. 

I.  North  America. 

1.  General  Character.  North  America  has,  in  the  eastern 
half,  a  greater  amount  of  rain  than  either  of  the  other  northern  con- 
tinents, in  similar  latitudes.  Though  the  primary  highlands,  which 
lie  in  the  western  part,  across  the  track  of  the  return-trades,  oppose 
the  entrance  of  the  moisture  from  the  Pacific  into  the  interior ;  yet 
the  great  sub-tropical  basin  of  the  Gulf  of  Mexico  sends  up  into  the 
air  its  wealth  of  vapors,  to  replace  those  lost  by  the  winds  in  cross- 
ing the  high  mountain  chains.  ^ 

Hence  the  eastern  portions,  —  the  great  basins  of  the  Mississippi 
and  the  St.  Lawrence,  and  the  Appalachian  region,  —  which  with- 
out this  source  of  moisture  would  be  doomed  to  drought  and  bar- 
renness, are  the  most  copiously  watered  and  the  most  productive 
portions  of  the  continent. 

2.  Arid  Regions.  The  plateau  of  Mexico  and  the  peninsula  of 
California  —  situated  in  the  sub-tropical  zone ;  —  the  interior  pla- 
teaus east  of  the  Sierra  Nevada  ;  and  a  narrow  belt  of  the  high 
plains  east  of  the  Rocky  Mountains,  south  of  42°  north  latitude,  are 
the  only  exceptions  to  the  abundance  of  moisture  which  character- 
izes this  most  favored  continent.  Even  these  regions  are  not  entirely 
rainless,  but  receive,  to  some  extent,  the  winter,  equinoctial,  or  sum- 
mer rains  belonging  to  their  several  latitudes. 

II.    I. Ill  <»|M'. 

1.  General  Character.  Europe  is  well  watered  throughout, 
with  the  exception  of  a  narrow  region  of  steppes  adjacent  to  the 
Caspian  Sea.  But,  excepting  a  few  points  immediately  on  the 
Atlantic  and  Mediterranean  coasts,  the  average  annual  rainfall  in 
Europe  is  several  inches  less  than  in  North  America. 

2.  Exceptional  Regions.  The  places  which  receive  most 
abundant  rains  are  Coimbra,  at  the  foot  of  the  mountains,  on  the 
western  coast  of  Portugal ;  Bergen,  on  the  Scandinavian  coast ;  Ba- 
yonne,  at  the  head  of  the  Bay  of  Biscay  ;  Tolmezzo,  at  the  head  of 
the  Adriatic  Sea  ;  and  Seathwaite,  on  the  west  coast  of  England,  in 
the  Cumberland  Mountains. 


92 


SNOW. 


Peculiarities  of  relief  explain  the  exceptional  rainfall  of  these  re- 
gions. At  Tolmezzo,  for  example,  an  arc  of  high  mountains  encom- 
passes the  head  of  the  Adriatic,  on  the  side  opposite  the  wind ;  and 
condenses,  upon  a  small  area,  all  the  vapors  brought  within  its  cir- 
cumference. At  Seathwaite  the  isolated  mountain  group,  rising  into 
the  region  of  clouds,  performs  the  same  work.  Similar  conditions 
exist  at  each  of  the  other  places  named. 


III.  Asia. 

1.  General  Character.  Asia,  the  greatest  and  the  coldest  of 
the  land  masses,  with  the  loftiest  mountains  and  the  largest  plateaus, 
has,  regarded  as  a  whole,  less  rain  than  any  other  of  the  northern 
continents.  The  main  slope,  which  includes  the  whole  continent 
with  the  exception  of  the  southern  peninsulas,  is  directed  towards  the 
north  ;  and  is  open  to  the  dry  polar  winds,  while  the  moist  return- 
trades  are  shut  out  from  it. 

In  the  zone  of  perennial  rains  less  water  falls  than  in  the  corre- 
sponding zone  of  Europe.  In  the  zone  of  semi-periodical  rains, 
where  the  surface  consists  mainly  of  mountain-girdled  plateaus  or 
sandy  marine  plains,  little  rain  falls  except  on  the  mountains.  The 
regions  of  greatest  rainfall,  in  the  latter  zone,  are  Asia  Minor,  the 
Caucasus,  and  the  Caspian  shores,  in  western  Asia  ;  the  Thian  Shan, 
and  Pamir,  in  the  centre  ;  and  middle  and  north  China,  in  the  east. 

The  plateau  of  Arabia,  the  adjacent  table-lands  of  Syria  and 
Iran,  and  the  vast  plateau  of  Mongolia,  have,  in  general,  but  scanty 
rains.  They,  with  the  Sahara,  form  a  great  central  belt  of  deserts, 
extending  from  the  Atlantic,  in  Africa,  nearly  to  the  Pacific  shores 
in  Asia. 

2.  Periodical  Rains.  The  southern  part  of  China,  the  penin- 
sulas of  India  and  Indo-China,  the  southeast  coast  of  Arabia,  and 
the  Indian  Archipelago,  lie  in  the  zone  of  periodical  rains.  Here  the 
rains,  which  are  copious,  accompany  the  monsoons ;  and  the  opposite 
coasts  of  the  great  Indian  peninsulas  receive  rain  at  opposite  seasons. 
Even  on  these  favored  shores,  however,  except  at  a  few  points  where 
locaj  peculiarities  of  relief  give  an  amount  of  rain  entirely  unparal- 
leled, the  rainfall  is  less  than  on  the  coasts  and  islands  of  tropical 
America. 

The  interior  of  the  Deccan,  a  plateau  surrounded  with  mountains, 
receives  little  rain.  On  the  Arabian  shores,  though  there  is  an  abun- 
dance of  rain,  yet  as  it  falls  in  a  single  season,  usually  with  great 
violence,  and  flows  away  almost  immediately,  it  benefits  the  soil  but 
little.     Only  the  valleys  are  permanently  watered. 

Cherraponjee,  near  the  head  of  the  Bay  of  Bengal,  in  the  Cossyah 
Mountains,  which  rise  isolated  from  the  low  plains  of  India,  receives 
the  greatest  fall  of  rain  on  record,  viz.,  610  inches.  At  Mahabu- 
leshwur,  in  the  Western  Ghauts  of  India,  4,500  feet  above  the  sea 
level,  254  inches  of  rain  have  been  recorded. 


ANALYSIS   OF  SECTION   X. 

I.  North  America. 

1.  General  Character. 

2.  Arid  Regions. 

II.  Europe. 

1.  General  Character. 

2.  Regions  of  Greatest  Rainfall. 


2.  Zone  of  Periodical  Rains. 

a.  Regions  included. 

b.  Time  of  rain.    Amount. 
e.  Rain  in  the  Deccan. 

d.  Regions  of  excessive  rain. 


XI.  —  SNOW. 


III.  Asia. 


1.  General  Character. 

a.  Cause  of  scarcity  of  rain. 

b.  Moisture  in  zone  of  perennial  rains. 

c.  Moisture  in  zone  of  semi-periodical  rains. 


Rainless  regions. 


I.  Formation. 

Vapor  condensed  in  air  having  a  temperature  below  32°  Fahr. 
freezes,  or  passes  to  a  crystalline  form,  producing  snow.  Snow-flakes 
occur  in  a  great  variety  of  forms,  which  usually  present  the  outline 
of  either  a  regular  hexagon  or  a  six-pointed  star. 

Their  size  depends  upon  the  temperature  and  the  relative  humid- 
ity of  the  air  through  which  they  fall ;  for,  like  raindrops,  they  in- 
crease by  successive  additions  from  the  vapors  with  which  they  come 
in  contact  in  descending.  Thus  in  mild  weather  they  are  much 
larger  than  in  very  cold  weather. 

When  the  lower  air  is  warm  enough  partially  to  melt  the  crys- 
tals, they  form  minute  balls.  When  raindrops,  formed  in  the  upper 
air,  fall  through  a  cold  current,  they  are  often  frozen,  producing 
sleet  instead  of  snow. 

II.  Horizontal  Distribution. 

In  high  and  middle  latitudes,  the  ground  is  covered  with  snow 
each  winter  ;  but  within  the  tropical  regions  no  snow  falls  at  or  near 
the  level  of  the  sea,  for  the  temperature  of  the  lower  atmosphere  is 
always  sufficient  to  melt  the  crystals,  even  if  they  are  formed  in  the 
upper  air. 

In  the  northern  hemisphere  the  limit  of  the  fall  of  snow  at  the  sea 
level,  is  an  irregular  line  lying  mainly  between  25°  and  40°  north 
latitude ;  in  the  southern  it  is  somewhat  regular,  lying  about  lati- 
tude 43°  in  the  oceans,  and  from  32°  to  38°  in  the  continents. 

In  general,  this  line  is  nearest  to  the  equator  in  the  regions  most 
exposed,  in  winter,  to  polar  winds ;  as  on  the  eastern  coast  of  Asia 
and  North  America. 

The  period  of  continuance  of  snow  increases,  with  the  distance 
from  the  limit  of  snow  fall.  Rome,  for  example,  has  an  average  of 
one  and  one-half  snowy  days  in  the  year ;  Paris  has  twelve,  Copen- 
hagen thirty,  and  St.  Petersburg  one  hundred  and  seventy-one. 

The  quantity  of  snow  falling  annually  is  greatest  in  cool-temper- 
ate latitudes,  since  the  amount  of  vapor  in  the  air  within  those 
regions  is  greater  than  in  the  polar  regions. 

As  the  warmth  of  the  air  diminishes  upward,  a  temperature  per- 
mitting the  fall  of  enow  may  always  be  found  upon  high  mountains, 
even  under  the  equator. 

At  the  summit  of  the  Andes,  for  example,  the  moisture  which  is 
condensed  during  the  rainy  season  falls  in  the  form  of  snow,  while 
the  slopes,  and  the  plains  at  their  foot,  are  drenched  with  rain. 

III.  Permanent  Snow. 

1.  Where  Found.  Though  the  winter  snows  upon  the  plains, 
and  the  slopes  of  mountains  of  medium  height,  disappear  during  the 
warm  season  ;  yet,  in  all  latitudes,  the  tops  of  high  mountains  are 
covered  with  a  layer  of  permanent  snow,  which  the  summer  heat  of 
these  great  altitudes  is  not  sufficient  to  melt. 

The  lower  limit  of  perpetual  snow,  called  the  snow  line,  is  found, 
within  the  tropics,  about  three  miles  above  the  level  of  the  sea.  In 
temperate  latitudes  it  occurs  at  the  height  of  a  little  less  than  two 


miles  ;  and  at  the  northern  limit  of  the  continents,  it  is  about  half 
a  mile  above  the  level  of  the  sea  or,  perhaps,  even  less  than  this. 

On  the  Arctic 
islands,  vast  fields 
of  snow  remain  per- 
manently, at  a  few 
hundred  feet  above 
the  sea  level. 

The  winter 
snows,  falling  into 
the  icy  waters  of  the 
polar  oceans,  are  but 
partially  dissolved ; 
and,  remaining  up- 
on the  freezing  sur- 
face, they  help  to 
form  those  vast  ice 
floes  which  encum- 
ber the  polar  seas 
at  all  times. 

2.  Height  of 
the  Snow  Line. 
The  following  table 
gives  the  observed 
height  of  the  snow 
line  in  the  different 
latitudes :  — 


GLACIER  OF   ZER1IATT,    MONTE   ROSA,    CENTRAL   ALPS. 


Lat,  N. 


75° 

54° 
48° 
43' 
39' 
38° 
19° 
5° 
Lat.  S.  V 
17° 
17" 
33' 
42° 
54° 


New  World. 


about 


North  Greenland 
Unalashka  .  .  . 
Mt.  Baker,  Oregon 
Rocky  Mountains  . 
Rocky  Mountains  . 
Sierra  Nevada  .  . 
Popocatepetl,  Mexico 
Tolima,  Columbia  . 
Andes  of  Ecuador  . 
Andes  of  Bolivia,  west  side 
Andes  of  Bolivia,  east  side 
A  tide-  of  central  Chili  .  . 
Amirs  of  Patagonia  .  . 
Andes  of  Straits  of  Magellan 


Kng.  ft. 

Lat.  N. 

2,300 

75' 

3,500 

71° 

8,000 

67° 

12,500 

61° 

14,500 

50° 

11,000 

46° 

14,900 

46° 

15.300 

43° 

15,800 

35° 

18,500 

31' 

15.700 

" 

14,700 

12° 

6,000 

Lat.  S.  3° 

3,700 

44" 

Old  World. 


Baer  Island  .... 
Mageroe,  Cape  North  . 
Sulitelma,  Lapland 
Scandinavian  Alps  .  . 
Altai  Mountains  .  . 
Alps,  north  side  .  . 
Alps,  south  side      .     . 

Caucasus 

Hindo  Koosh  .... 
Himalaya,  south  side  . 
Himalaya,  north  side  . 
Abyssinian  Mountains 
Kilima-Njaro  .... 
New  Zealand  Alps    .     . 


Eng.  ft. 


600 

2,300 

3,800 

6,300 

7,000 

8,800 

9,200 

11,000 

13,000 

16,200 

17,400 

14,000 

16,000 

7,500 


The  snow  line  was  formerly  supposed  to  be  a  curve  coinciding 
with  the  vertical  isothermal  of  32°  Fahr.  —  the  freezing  point  —  and 
rising  regularly,  with  the  average  temperature,  from  the  polar  re- 
gions to  the  equator.  Neither  supposition  has  proved  to  be  entirely 
correct.  The  mean  temperature  of  the  air  at  the  snow  line  is,  ac- 
cording to  observation,  several  degrees  below  the  freezing  point ;  and 
the  table  shows  that  this  line  is  subject  to  great  irregularities  of  ele- 
vation, also  that  its  extreme  altitude  is  not  at  the  equator,  but  in  the 
vicinity  of  the  tropics. 

8.  Irregularities  in  Elevation.  The  elevation  of  the  snow 
line  depends  upon  two  conditions  :  the  quantity  of  snow  which  falls, 
and  the  amount  of  heat  there  is  to  melt  it.  Neither,  alone,  but  the 
relation  between  the  two,  determines  the  limit  of  perpetual  snow. 
Thus  in  the  subtropical  zones,  which  have  less  snow,  with  no  less 
summer  heat,  the  snow  line  is  higher  than  at  the  equator. 

In  similar  latitudes  the  coast  regions,  exposed  to  moist  winds,  have 
a  lower  snow  line  than  the  interior  of  the  continents,  with  their 
scanty  snows,  dry  atmosphere,  and  hot  summers.  The  peaks  of  the 
Sierra  Nevada  bear  perpetual  snow,  3,500  feet  lower  than  the  Rocky 
Mountains,  in  the  same  latitude.     The  south  slope  of  the  Himala- 


yas, which  condenses  the  abundant  vapors  brought   by  the  warm 
monsoons,  has  a  snow  limit,  on  an  average,  2,000  feet  lower  than 

the  north  slope,  on 
the  dry  and  sunny 
plateau  of  Thibet. 

In  the  Alps, 
which  are  well 
watered  on  both 
sides,  the  limit  of 
snow  is  somewhat 
higher  on  the  south- 
ern slope  ;  for  here 
the  exposure  to  the 
warm  summer 
winds  more  than 
compensates  for  the 
slight  excess  in  the 
a  m  o  u  n  t  of  snow 
which  falls  on  t  h  e 
south  side. 

In  passing  from 
the  dry  climate  of 
central  Chili  to  the 
rainy  region  farther 
south,  the  snow 
line  descends  from 
14,700  feet  to  6,000. 
A  vast  amount  of  snow  in  the  latter  region,  and  a  wet  and  cloudy 
summer,  account  for  the  change.  In  the  Rocky  Mountains,  in  a  lat- 
itude corresponding  to  that  of  the  Patagonian  Andes,  the  snow  line 
has  an  altitude  of  12,500  feet. 


ANALYSIS  OF  SECTION  XI. 

I.  Formation. 
II.  Horizontal  Distribution. 

a.  Snow  in  tropical  regions. 

b.  Limit  of  snow  at  sea  level. 

In  northern  hemisphere. 
In  southern  hemisphere. 

c.  Period  of  continuance  of  snow. 

d.  Amount  of  snow  falling.    Snow  on  elevation*. 

III.  Permanent  Snow. 

1.  Wberjs  Found. 

a.  In  tropics. 

b.  In  temperate  and  polar  regions. 

2.  Snow  Link. 

a.  Table  of  altitudes. 

b.  Former  supposition  regarding  snow  lines. 
8.  Explanation  op  Irregularities. 

a.  Altitude  depends  on  what. 

b.  Region  of  highest  snow  line. 

c.  Snow  line  in  coast  regions. 

d.  Snow  line  on  opposite  sides  of  Himalayas  and  Alps. 

e.  Snow  line  in  southern  Andes. 


XII.  — GLACIERS. 

I.  Nature  and  Aspect. 

Glaciers  (from  the  French  glaee,  ice)  are  vast  streams  of  ice  which 
descend  from  the  lower  edge  of  the  perpetual  snows,  like  long  icicles 
from  a  snow-covered  roof.  They  follow  the  windings  of  the  Alpine 
valleys,  and  terminate  abruptly  in  a  massive  wall  of  ice,  from  beneath 
which  the  waters  of  the  melting  glacier  escape,  through  a  large  icy 
vault.     (See  illustrations  on  this  and  the  following  page.) 


94 


GLACIERS. 


The  great  glaciers  of  the  Alps  extend  downwards  from  3,000  to  6,000  feet  below 
the  snow  line,  and  are  from  ten  to  fifteen  miles  in  length.  They  are  thus  a  beau- 
tiful provision  for  discharging,  from  the  regions  of  perpetual  frost,  the  excess  of 
snow,  in  order  that  it  may  melt  in  the  more  genial  atmosphere  below.  All  the  main 
Alpine  streams  —  the  Rhine,  the  Rhone,  the  Aar,  and  others  —  have  their  origin 
in  the  glaciers  ;  and  both  these  rivers  and  the  lakes  through  which  they  pass  have 
high  water  in  summer,  when  the  melting  of  the  ice  and  snow  is  most  rapid. 

When  the  slope  is  gentle,  the  surface  of  the  glacier  is  compara- 
tively smooth.  When  it  becomes  precipitous,  the  mass  of  ice  breaks 
up,  deep  crevices  open,  and  the  glacier  assumes  the  form  of  a  gigan- 
tic frozen  cataract ;  but  beyond  the  precipice  it  becomes  even  again. 

The  illustration  on  page  93  shows  the  smooth  part  of  the  great  glacier  of  Monte 
Rosa,  in  the  valley  of  Zermatt,  the  moraines  upon  its  surface,  and  the  formation  of 
crevices  at  the  head  of  a  rapid  slope.  Below  is  shown  the  shattered  mass,  resolved 
into  sharp  ice-needles,  as  they  are  called;  also  the  terminal  wall  of  the  glacier,  with 
its  vault,  and  the  stream  issuing  from  beneath. 

Glaciers  of  the  first  order  fill  the  main  valleys,  and,  like  the  great 
river  systems,  are  usually  composed  of  several  tributaries,  or  glaciers 
of  the  second  order,  which  unite  in  one  channel  But  the  ice  does  not 
blend,like  the  water, in  confluent  streams.  The  se  v  eral  d  ■.<  ners,  though 
strongly  compressed,  are  united  only  by  their  margins  ;  and  each  pre- 
serves its  individual  structure,  of- 
ten to  the  end  of  its  journey. 


II.  Formation. 

The  first  condition  for  the  for- 
mation of  a  glacier,  is  an  accumu- 
lation of  snow  which  can  be  but 
partially  melted  by  the  heat  of 
mimmer.  Such  accumulations  are 
favored  by  the  structure  of  the 
great  Alpine  valleys,  most  of 
which  expand,  within  the  region  of 
perpetual  snow,  into  vast  amphi- 
theatres ;  each  forming  an  im- 
m  e  n  s  e  common  reservoir,  into 
which  the  surrounding  peaks  all 
send  down  their  loads  of  snow. 

The  process  of  gradual  formation  is  indicated  by  the  variations  in  the  substance 
of  the  glacier  in  different  parts  of  its  course.  In  the  cold,  frosty,  upper  regions, 
the  snow,  composed  of  small  crystals  as  yet  unmelted,  is  dry  and  powdery.  Lower 
down,  a  partial  melting  and  agglomeration  of  the  crystals,  converts  them  into 
coarse,  white  grains,  forming  the  neve  (from  the  French  neige,  snow),  which  is 
always  found  somewhat  below  the  snow  line. 

The  melting  process  continuing,  the  neve"  is  gradually  soaked  by  the  percolating 
waters ;  and,  under  the  influence  of  freezing  nights  and  constant  pressure,  it  at 
length  becomes  a  consolidated  mass,  like  a  frozen  snow-bank  in  spring.  This  is 
the  beginning  of  the  glacier  proper. 

Still  lower,  regular  lamina;  of  transparent  ice  appear  in  the  mfdst  of  the  frozen 
snow ;  and  gradually  the  alternate  melting  and  refreezing,  under  high  pressure, 
converts  the  whole  into  the  blue  transparent  ice  which  forms  the  lower  portion  of 
the  glacier.     The  surface  alone,  owing  to  constant  disintegration,  appears  whitish. 

Glacier  ice,  however,  never  loses  the  traces  of  its  origin,  but  a  blow  of  the  ham- 
mer will  cause  it  to  crumble  to  pieces  and  reveal  its  granular  structure.  This  ex- 
plains how  the  water  from  the  melting  surface  can  pervade  the  entire  mass,  and 
render  its  particles  movable,  thus  facilitating  its  gradual  descent. 

HI.  Motion. 

Glaciers  descend  constantly  along  the  valleys  they  occupy,  though 
with  an  irregular  velocity.  As  in  streams,  a  more  rapid  slope,  or  a 
greater  mass,  accelerates,  and  a  more  gentle  slope,  or  a  smaller  mass, 
retards  the  motion. 


TERMINATION  OF  THE   GLACIER   OF    ZEKMATT. 


The  rate,  varying  in  different  glaciers,  is  always  greater  in  sum- 
mer than  in  winter  ;  and  is  greatest  when  the  melting  is  most  rapid. 
In  glaciers  of  the  first  order,  the  ordinary  progress  is  from  ten  to 
twenty  inches  a  day ;  but  sometimes,  as  observed  in  the  Mer  de 
Glace,  on  Mont  Blanc,  it  reaches  two  feet  or  more. 

The  bottom  and  sides  are  retarded  by  friction  against  the  rocky  walls  of  the 
.  while  the  top  and  centre,  moving  more  freely,  are  more  and  more  in  ad- 
vance. Hence  the  lower  end  of  the  glacier,  when  free  to  expand  — as  that  of  the 
Rhone,  in  Switzerland  —  terminates  in  a  convex  semicircle. 

The  termination  of  a  glacier,  notwithstanding  the  constant  de- 
scent, occupies  from  year  to  year  about  the  same  average  position  ; 
for  the  melting  in  summer  is  generally  sufficient  not  only  to  dissolve 
the  extremity  as  rapidly  as  it  advances,  but  also  to  remove  what  has 
been  gained  during  the  previous  winter. 

Heavy  snows,  however,  followed  by  a  cloudy  and  cool  summer, 
which  dimijjjshes  the  amount  of  melting,  may  permit  the  glacier  to 
extend  beyond  its  usual  limit ;  while  a  dry  winter,  or  an  unusually 
hot  and  clear  summer,  may  reduce  both  the  length  and  thickness 
below  the  average.  In  the  latter  case,  the  waste  during  the  sum- 
mer exceeds  the  gain  during  the  winter. 


IV.  Transportation  of  Rocks. 

Glaciers,  like  mountain  tor- 
rents, transport  fragments  of  rock, 
of  all  sizes,  which  have  gradually 
crumbled  from  the  uncovered 
peaks  and  slopes  above  them.  But 
owing  to  the  slow  and  steady  mo- 
tion, the  arrangement  of  these 
debris  is  entirely  different  from 
that  of  materials  transported  by 
water. 

1.  Moraines.  On  the  surface 
of  all  great  glaciers  (see  page  93) 
are  narrow  and  well  defined  bands 
of  rocks  and  rubbish,  called  mo- 
raines. They  are  both  lateral, 
lying  along  the  sides,  and  medial,  in  the  centre  of  the  glacier.  The 
latter  either  come  from  rocks  in  the  upper  part  of  the  valley,  or  are 
formed  by  the  united  lateral  moraines  of  confluent  glaciers. 

As  the  ice  melts,  at  the  end  of  the  glacier,  the  rocks  fall  to  the 
ground  ;  and,  with  pebbles  and  mud  from  beneath  it,  form  a  termi- 
nal moraine.  This  is  sometimes  of  great  height,  and  is  usually  in 
the  form  of  a  semicircular  wall  across  the  valley. 

A  surface  moraine,  whether  lateral  or  medial,  is  composed,  from  beginning  to 
end,  of  the  same  kinds  of  rock,  often  of  one  or  two  kinds  only ;  and  two  moraines 
lying  side  by  side  may  be  formed  of  rocks  of  an  entirely  different  nature;  for 
each  brings  the  debris  from  a  different  part  of  the  valley,  sometimes  from  a  single 
crumbling  peak.  These  broken  fragments,  falling  one  after  the  other  on  the  same 
spot,  are,  by  the  steady  advance  of  the  glacier,  successively  carried  down  along 
the  same  line,  to  the  terminal  moraine,  which  receives  them  all. 

2.  Action  of  Glaciers  on  their  Beds.  The  constant  friction  of  these  vast 
masses  of  ice  on  the  surface  of  their  rocky  beds,  rounds  off  the  projections  over 
which  they  pass,  and  smooths  and  polishes  even  hard  granite  and  marble.  The 
fine  mud,  composed  of  the  hardest  particles  of  these  crystalline  rocks,  adhering  to 
the  ice,  is  the  polishing  powder.  Coarser  grains  cut,  on  the  polished  surface,  sys- 
tems of  fine  parallel  scratches ;  and  larger  pebbles  form  long  parallel  furrows,  all 
indicating  the  direction  of  the  moving  ice. 

Old  moraines,  polished  and  grooved  rocks,  and  other  evidences  of  glacier  action, 
so  different  from  that  of  water,  show  that,  in  a  time  long  past,  vast  and  thick  gla- 
ciers existed  in  New  England  and  other  parts  of  North  America,  and  in  Europe 
where  no  permanent  snows  are  now  found. 


OPTICAL  AND   LUMINOUS   PHENOMENA. 


95 


V.  Geographical  Distribution. 

The  mountain  systems  in  the  middle  latitudes,  with  abundant 
snows  and  alternate  warm  and  cold  seasons,  are  most  favorable  to 
the  formation  of  glaciers.  The  best  known,  and  probably  the  most 
remarkable  glacier  region  is  that  of  the  high  Alps,  in  the  heart  of 
which  are  Mont  Blanc,  Monte  Rosa,  and  the  Bernese  Alps. 

The  Pyrenees  have  glaciers  of  the  second  order  only.  Late  explorers  have 
found  large  glaciers  in  the  Caucasus  and  in  the  Himalayas,  the  last  being  of  the 
grandest  proportions.  In  the  Scandinavian  Alps  are  many  which  descend,  in  the 
deep  western  fiords,  nearly  to  the  sea  level. 

In  the  New  World  glaciers  are  less  frequent.  They  are  entirely  wanting  in  the 
tropical  Andes,  the  constancy  of  temperature  throughout  the  year,  as  well  as  the 
structure  of  the  snow-covered  peaks, 
being  unfavorable  to  their  formation. 
In  the  snowy  Patagonian  Andes,  how- 
ever, they  are  numerous  and  well  defined. 

In  the  high  Sierra  Nevada,  polished 
and  grooved  rocks,  and  old  moraines, 
showing  the  former  presence  of  great 
glaciers,  are  found  down  to  4,000  feet 
above  the  sea  level ;  but  no  glaciers  have 
been  discovered.  Farther  north,  on 
Shasta  Peak  and  Mt.  Rainier,  genuine 
glaciers  of  the  second  order  have  been 
noticed. 

By  far  the  most  extensive  glaciers,  how- 
ever, are  found  on  the  snow-covered 
islands  of  the  polar  oceans.  The  gigan- 
tic Humboldt  glacier,  discovered  by  Dr. 
Kane  on  the  shores  of  Smith  Sound,  is 
sixty  miles  in  breadth,  rises  three  hun- 
dred feet  above  the  water,  and  extends 
an  unknown  distance  into  the  interior. 
Similar,  though  perhaps  less  extensive, 
glaciers  occupy  nearly  all  the  valleys  of 
Greenland,  Spitzbergen,  and  other  Arc- 
tic and  also  Antarctic  islands. 

Vast  masses  of  ice,  broken  from  the 
ends  of  these  glaciers,  form  the  enormous 
icebergs  (mountains  of  ice)  which  are  so 
numerous  in  the  polar  seas,  and  are 
transported  by  the  currents  even  to  middle  latitudes 
in  map,  pages  28,  29.) 


THE  AURORA  BOREALIS. 


(See  Limit  of  drifting  ice, 


ANALYSIS   OP   SECTION   XII. 
I.  Nature  and  Aspect. 


II.  Formation. 


HI.  Motion. 


a.  Character,  extent,  and  termination. 

b.  Surface. 

c.  Situation  and  composition  of  great  glaciers. 

a.  Condition  of  formation. 

b.  Process  how  indicated.    Appearance  of  mountain  snows. 

Structure  of  different  parts  of  glacier. 
Peculiarity  of  glacier  ice. 

a.  Continuity  and  irregularity  of  progress. 

b.  Uate  in  different  seasons.     Average  rate. 

c.  Termination. 


Bottom  and  tides. 


TV.  Transportation  of  Rocks. 

1.  Moa.usres  or  what  formed. 

a.  Surface  moraines  how  situated. 

b.  Terminal  moraines. 

2.  Actiox  or  Glaciers  os  their  Beds. 
T.  Geographical  Distribution. 

a.  Most  noted  glacier  region. 

b.  Other  glacier  regions  of  Old  World. 

c.  Glaciers  in  New  World. 

d.  Most  extensive  glaciers.     Icebergs. 


XIII.  —  OPTICAL  AND   LUMINOUS   PHENOMENA. 
I.  Introduction. 

A  number  of  striking  phenomena,  both  optical  and  luminous,  arise  from  the 
physical  properties  of  the  atmosphere.     The  explanation  of  them  belongs,  however, 


to  the  subject  of  natural  philosophy  rather  than  physical  geography,  for  the  latter 
investigates  the  atmosphere  only  as  furnishing  the  conditions  of  life  upon  the  globe. 
Hence,  they  will  be  touched  upon  here  only  in  a  very  general  way. 

II.  Optical  Phenomena. 

1.  Rainbows  are  arches  of  prismatic  colors  formed  by  the  reflection  of  rays  of 
light  from  within  drops  of  water.  The  rays,  which  are  refracted  in  entering  the 
drops,  are  reflected  from  their  posterior  surfaces,  and  again  refracted  as  they  re- 
enter the  air,  the  colors  being  separated  by  their  unequal  refrangibility. 

2.  Ha  i,os  and  coronas  are  circles  of  prismatic  colors  which,  in  certain  states 
of  the  atmosphere,  surround  the  Sun  and  the  Moon. 

Halos  are  supposed  to  be  occasioned  by  the  presence,  in  the  atmosphere,  of 
small  ice  crystals  which  act  as  minute  prisms,  decomposing  and  refracting  the 

light  which  passes  through  them.  Their 
size  is  fixed,  as  they  are  seen  only  under 
a  visual  angle  of  either  22°  or  46°. 

Coronas  are  seen  when  a  light  mist  is 
floating  in  the  air,  and  are  supposed  to  be 
formed  by  reflection  from  the  external 
surface  of  the  globules  of  vapor. 

3.  Colors  or  the  Sky  and  Clouds. 
The  azure  tint  of  the  cloudless  sky  is  due 
to  the  decomposition  and  refraction  of 
light,  as  it  passes  through  layers  of  air 
successively  increasing  in  density.  The 
blue  and  violet,  being  more  refrangible 
than  other  colors  of  the  solar  spectrum, 
are  diffused  through  the  atmosphere ;  and 
being  reflected  from  its  particles,  they 
impart  to  it  their  own  color. 

The  clouds  floating  in  the  atmosphere 
absorb  the  more  refrangible  rays,  and  re- 
flect the  less.  At  sunrise  and  sunset, 
when  the  light  traverses  the  greatest 
depth  of  atmosphere,  all  the  colors  are 
absorbed  except  the  red  and  the  yellow  ; 
and  these,  being  reflected  from  the  parti- 
cles of  vapor,  produce  the  brilliant  color- 
ing of  the  evening  and  morning  clouds. 

4.  The  Mirage  is  an  optical  phenom- 
enon in  which  images  of  distant  objects 
are  seen,  reflected  beneath,  or  suspended 

Occasionally,  also,  objects  are  seen  double,  being  repeated 


in  the  heavens  above 
laterally  instead  of  vertically. 

The  mirage  is  caused  by  the  refraction  and  reflection  of  light  as  it  passes  from 
denser  to  rarer  strata  of  air.  It  is  most  frequent  in  arid  plains,  where  the  soil,  ex- 
posed to  the  burning  rays  of  the  sun,  becomes  intensely  heated,  and,  in  conse- 
quence, the  strata  of  air  near  the  ground  are  less  dense  than  those  above. 

In  this  case  rays  of  light  passing  from  any  distant  object,  as  a  tree,  to  the 
ground,  are  refracted  more  and  more  towards  the  horizontal,  until  finally  they 
are  reflected  from  a  horizontal  layer  of  the  heated  air,  and  reach  the  eye  from  be- 
neath. Then  an  image  of  the  object  is  seen  as  if  mirrored  in  the  tranquil  waters 
of  a  lake. 


III.  Luminous  Phenomena. 

1 .  Lightning  is  the  dazzling  light  produced  by  an  electrical  discharge  passing 
between  clouds  which  are  oppositely  electrified,  or  between  the  clouds  and  the 
Earth.  Lightning  flashes  have  been  distinguished  as  zigzag  or  chain  lightning, 
sheet,  and  globular  lightning. 

The  first  has  the  aspect  of  a  sharply  defined  chain  of  fire,  and  moves  at  the 
rate  of  250,000  miles  per  second.  Its  zigzag  course  is  attributed  to  the  resistance 
of  the  air,  condensed  in  the  passage  of  the  electrical  discharge,  which  is  sufficient  to 
turn  it  aside  frequently  in  the  direction  of  less  resistance. 

Sheet  lightning  includes  the  expanded  flashes  which  occur  during  a  storm ;  and 
the  heat  lightning,  seen  on  summer  evenings,  when  no  clouds  are  visible,  which 
is  supposed  to  be  the  reflection  of  a  storm  taking  place  below  the  horizon. 

Globular  lightning  is  seen  on  rare  occasions,  when  the  electrical  discharge  takes 
the  form  of  a  ball  of  fire,  and  descending  with  less  rapidity,  is  visible  for  several 
seconds.     In  certain  conditions  of  the  atmosphere,  globes  or  spires  of  electrical 


96 


OPTICAL   AND  LUMINOUS   PHENOMENA. 


light,  called  St.  Elmo's  fire,  are  seen  tipping  the  extremities  of  bodies  in  contact 
with  the  earth,  like  church  spires,  or  masts  of  ships. 

All  the  conditions  which  give  rise  to  electrical  excitement  in  the  atmosphere 
are  much  more  intense  in  warn  than  in  cold  latitudes ;  hence  the  thunder-storms 
of  the  tropical  regions  greatly  exceed,  both  in  frequency  and  in  violence,  those  of 
temperate  and  cold  climates. 

2.  The  Aurora  Borealis,  or  northern  light,  is  a  phenomenon  frequently  ob- 
served in  the  northern  heavens.  It  occurs  in  many  forms,  but  the  most  common 
is  that  of  a  luminous  arch    (see  page  95)  whose  summit  is  in  the  magnetic  me- 


ridian of  the  place  of  observation,  and  from  which  vivid  flashes  of  light  dart  to- 
wards the  zenith.  A  like  phenomenon  in  the  southern  heavens  is  denominated 
the  Aurora  Australis.  Auroras  arc  most  frequent  and  brilliant  in  the  polar  regions 
and  diminish  in  intensity  towards  the  equator. 

The  constant  relation  existing  between  the  arch  and  the  magnetic  meridian, 
together  with  the  oscillation  of  the  magnetic  needle  during  the  auroral  display, 
suggests  the  idea  that  this  phenomenon  is  caused  by  electrical  currents  in  the 
higher  atmosphere.  But  no  explanation  thus  far  proposed,  can  be  accepted  as 
entirely  satisfactory. 


REVIEW   OF   PART   IV. 


I. 


(69.)  How  is  the  weight  of  the  atmosphere  measured?     How  does  its  density  vary? 
At  what  distance  from  the  sea  level  is  the  weight  of  the  atmosphere  reduced  by  one-half? 
(70. )  What  is  the  height  of  the  atmosphere  ?    How  is  the  atmosphere  related  to  organic  life  ? 
Define  climate.     What  is  its  fundamental  phenomenon  ?     What  is  astronomical  climate  ? 
What  is  physical  climate,  and  on  what  does  it  depend  ? 

II. 

What  is  the  general  law  of  the  distribution  of  heat  upon  the  globe? 
What  are  the  causes  of  the  diminution  of  heat  from  the  equator  towards  the  poles? 
Explain  the  change  of  seasons,  and  the  variation  in  the  length  of  day  and  night? 
(71.)  What  effect  has  the  variation  in  the  length  of  the  day  upon  the  temperature  of  different 
seasons?     What  is  the  law  of  variation  in  the  inequality  of  day  and  night? 

What  is  the  result  of  this  variation?    What  are  the  seasons  in  the  different  zones? 
When  is  the  heat  greatest  in  middle  and  polar  latitudes?     Why? 

III. 

(72.)  What  are  isothermal  lines,  and  what  is  their  object? 

What  is  the  character  of  the  general  deviations  from  astronomical  climates,  and  how  are  they 
caused?    What  is  the  nature  and  extent  of  the  deviations  due  to  altitude? 

How  does  the  temperature  on  plateaus  compare  with  that  on  mountain  peaks  of  the  same 
altitude?    Why?    How  do  winds  and  marine  currents  modify  the  astronomical  climates? 

On  which  hemisphere  are  the  astronomical  climates  most  modified? 

Where  do  the  extreme  deviations  from  astronomical  climates  occur?    Give  examples. 

Explain  the  manner  in  which  these  deviations  are  produced. 

(73.)  How  do  the  eastern  and  western  coasts  of  the  southern  continents  compare?     Why? 

How  do  the  zones  of  physical  climate  differ  from  the  astronomical  zones?  State  the  limits 
of  the  several  physical  zones,  with  their  comparative  extent  in  the  different  continents. 

Describe  absorption  and  radiation  of  heat  by  water;  by  land.  What  is  the  result  upon  cli- 
mates ?  What  is  the  character  of  the  oceanic  climate  ?  Of  the  continental  climate  ?  Of  the 
coast,  or  maritime,  climate  ? 

To  what  extent  can  the  influence  of  the  continents  and  the  oceans  on  climate  be  traced  ? 

IV. 

(76.)  What  are  the  conditions  of  the  equilibrium  of  the  atmosphere?    What  is  the  result  of 
a  disturbance  of  the  equilibrium?     What  are  winds,  and  how  are  they  classified  and  named? 
Describe  and  name  the  general  currents  of  the  atmosphere.     How  are  they  caused? 
What  are  the  directions  of  the  polar  and  return  currents,  and  what  gives  these  directions? 
(77.)  What  local  causes  affect  the  general  directions  of  these  currents? 
What  zones  result  from  the  general  laws  of  atmospheric  circulation  ? 
What  are  the  trade  winds?     Where  do  they  blow  with  regularity,  and  why  only  there? 
Where  do  they  commence;  and  what  is  their  rate  of  motion? 

Define  and  explain  the  equatorial  zone  of  calms.  What  other  belts  of  calms  are  known  ? 
How  does  the  position  of  the  belts  of  trades  and  calms  vary  in  different  parts  of  the  year? 
What  general  land  winds  are  noticed  in  the  zones  of  trades  ? 


(78.)  What  are  monsoons?     Explain  the  monsoons  of  the  Indian  ocean? 

Explain  the  cause  of  the  diurnal  land  and  sea  breezes;  the  diurnal  mountain  breezes. 

What  periodical  winds  are  observed  in  the  neighborhood  of  great  deserts,  and  what  is  their 
direction?     (79.)  Describe  these  deserts,  winds,  and  their  effects. 

What  are  the  etesian  winds?  The  northers?  What  are  the  prevailing  currents  in  the  zone 
of  variable  winds?     What  is  the  effect  of  their  differing  temperatures  and  directions? 

In  what  order  do  the  normal  currents  displace  each  other  in  each  hemisphere? 

How  is  the  effect  of  the  transition  of  the  winds  manifested? 

What  are  the  starting-points  of  the  polar  winds,  and  why  in  these  regions? 

What  is  the  direction  of  the  coldest  winds  in  eastern  North  America,  and  why  ? 

What  change  takes  place  in  the  polar  winds  as  the  sun  advances  northward,  and  why? 

Describe  the  range  and  the  effects  of  the  polar  currents;  of  the  return  trades. 

VI. 

(82.)  What  are  cyclones?    What  is  the  direction  of  their  motions,  in  each  hemisphere? 

Where  do  the  West  India  hurricanes  originate,  and  what  is  their  cause? 

(83.)  Describe  the  course  necessary  to  escape  from  a  hurricane,  in  each  hemisphere. 

What  is  the  extent  of  the  cyclones,  and  when  are  they  most  frequent? 

How  can  the  northeasterly  storms  of  the  Atlantic  seaboard  be  explained? 

Describe  the  successive  changes  of  the  wind,  in  different  portions  of  the  area  of  those  storms. 

What  are  tornadoes?    Waterspouts?     (84.)  What  is  the  cause  of  the  tornadoes ? 


VII. 

Upon  what  does  the  capacity  of  the  air  for  receiving  vapor  depend  ?    What  is  saturation  ? 
How  can  the  relative  and  the  absolute  humidity  of  the  air  be  ascertained? 
How  ate  clouds  classified,  and  what  are  the  principal  forms  ?     Describe  each. 
(85.)  What  is  the  general  cause  of  condensation  and  rain?    Examples. 
What  is  the  effect  of  mountain  chains  on  the  condensation  of  vapors  ?     Examples. 
What  is  the  comparative  amount  of  rain  on  plateaus,  and  why?     What  influence  has  the 
nature  of  the  soil  on  the  condensation  of  the  vapor  in  the  air?     Advantage  of  forests? 
(88.)  How  does  the  average  annual  rainfall  vary  in  different  latitudes?     Why? 
How  does  the  amount  of  cloudiness,  and  the  number  of  rainy  days  in  the  year  vary  ?    Why  ? 
How  do  the  coasts  compare  with  the  interior  of  the  continents  in  moisture  ?     Why? 
How  does  the  New  World  compare  with  the  Old  in  its  average  rainfall  ?     Why  ? 
What  is  the  average  in  each,  in  both  temperate  and  tropical  latitudes? 

VIII. 

(89.)  What  peculiarity  in  regard  to  rains  characterizes  the  tropical  regions,  and  why? 

How  are  the  temperate  and  cold  regions  characterized,  and  why  ? 

Describe  the  rains  in  the  zone  of  calms.  When  do  the  rains  occur  in  the  zone  of  trades,  and 
why?    Describe  (lie  dry  season      The  rainy  season. 

What  is  the  time  of  rain  on  the  opposite  coasts  of  the  Deccan,  and.  why  ? 

(90.)  Describe  the  sub-tropical  belt.  What  is  the  time  and  cause  of  rain  in  the  warm  tem- 
perate zone?    In  the  temperate  proper?    In  the  polar  zone ? 

IX. 

What  is  the  relative  amount  of  rain  in  South  America? 

Describe  the  distribution  of  moisture  in  the  intertropical  region.     Beyond  the  tropics. 

Why  are  the  Peruvian  Andes  dry  on  the  western  slope,  and  those  of  southern  Chili  and 
Patagonia  on  the  eastern?  Why  are  the  Andes  of  northern  Chili  dry  on  both  slopes,  and  those 
of  Columbia  anil  Ecuador  wet  on  both? 

What  are  the  conditions  of  central  Africa  in  regard  to  rain,  and  why? 

Describe  the  distribution  of  rain  in  northern  Africa.     To  what  is  its  aridity  due? 

What  is  the  character  of  southern  Africa?     Of  the  continent  as  a  whole? 

What  is  the  relative  amount  of  rain  in  Australia,  and  the  time  of  rain  in  different  portions?     ! 

X. 

Describe  the  distribution  of  moisture  in  North  America. 

What  is  the  cause  of  the  dryness  of  the  western  plateaus?  How  would  the  distribution  of 
moisture  in  this  continent  be  affected  if  the  Gulf  of  Mexico  should  become  dry  ? 

What  is  the  distribution  and  comparative  amount  of  moisture  in  Europe  ? 

(92.)  How  do  you  explain  the  exceptional  rainfall  at  Tolmezzo?     At  Seathwaite? 

What  is  the  comparative  amount  of  rain  in  Asia,  and  why? 

Describe  the  distribution  of  moisture  in  the  zone  of  semi -periodical  rains.  How  do  you  ac- 
count for  the  extreme  inequality  of  rainfall  in  the  different  parts  of  this  region? 

Describe  the  distribution  of  moisture  in  the  region  of  periodical  rains.  Where  do  you  rind 
the  greatest  amount  of  rain  on  record  ?     How  can  you  explain  this  excessive  rainfall  1 

XI. 

In  what  regions  of  the  earth  does  snow  fall  at  the  sea  level  ?     Why  only  there? 

How  does  the  period  of  continuance  of  snow  vary  in  different  latitudes  ?  The  quantity  which 
falls?  What  is  the  average  altitude  of  the  snow  line  in  the  different  zones?  (93.)  Upon  what 
does  its  altitude,  in  any  region,  depend  ? 

Where  does  the  snow  line  have  its  greatest  altitude,  and  why  ?  How  does  its  altitude  in 
the  coast  regions  compare  with  that  in  the  interior  of  the  continents,  and  why  ? 

XII. 

What  are  glaciers?    (94.)  What  is  the  extent  of  the  great  glaciers  of  the  Alps? 

What  is  the  first  condition  of  the  formation  of  a  glacier?    Describe  the  process  of  formation. 

Describe  the  motion  of  the  glaciers.  What  prevents  the  descending  glacier  from  encroach-  j 
ing  on  the  lower  lands?    What  are  moraines,  and  how  are  they  formed? 

What  is  the  effect  of  glaciers  upon  the  rocks  in  their  bed? 

(95.)  What  regions  are  most  favorable  to  the  formation  of  glaciers?  Why?  When)  are  ] 
glaciers  most  extensive?     Why  are  glaciers  absent  from  the  tropical  Andes? 

XIII. 

Upon  what  do  the  luminous  and  optical  phenomena  of  the  atmosphere  depend? 

How  are  rainbows  formed  ?     What  are  halos  and  coronas,  and  how  are  they  formed  ? 

What  gives  the  cloudless  sky  its  blue  tint?    What  causes  the  brilliant  colors  of  the  clouds?    | 

What  is  the  mirage,  and  how  is  it  caused  ?    Where  is  it  most  frequent,  and  why  ? 

What  is  lightning?     What  is  the  velocity  of  zigzag  lightning? 

How  are  the  auroras  supposed  to  be  caused  ?     Where  are  they  frequent  and  brilliant  ? 


PART    V. 
LIFE    UPON    THE    EARTH. 


I  —  LIFE  IN  NATURE. 
I.  — INTRODUCTION. 

1.  The  System  of  Life  in  nature  is  represented  by  the  vegeta- 
ble and  the  animal  world ;  while  man  is  its  representative  in  the 
higher,  spiritual  sphere  of  the  mind. 

2.  Plants  and  Animals,  unlike  minerals,  grow  from  germs,  and 
develope  into  individuals,  with  definite  forms  and  organs.  After  a 
limited  existence,  they  die,  their  species  being  perpetuated  by  seed 
or  offspring.  The 
functions  of  plants 
and  animals  in  na- 
ture are,  however, 
entirely  unlike. 

The  plant,  alone, 
transforms  inorgan- 
ic into  organic  mat- 
ter, and  thus  pre- 
pares food  for  the 
animal.  In  its  quiet 
steady  growth,  it 
gathers  a  store  of 
force  which  the  an- 
imal expends  in  ac- 
tion. Thus  the  dis- 
tribution of  vegeta- 
tion regulates  that 
of  animal  life. 

The  animal,  be- 
ing called  upon  to 
move  and  act,  is  en- 
dowed with  sensa- 
tion and  will ;  but 
neither  is  required  in  the  passive,  motionless  life  of  the  plant. 

Vegetation  not  only  forms  the  indispensable  link  between  inor- 
ganic nature  and  animal  life ;  but  it  clothes  the  surface  of  the  land 
with  that  rich  mantle  of  verdure  and  flowers  which  is  its  greatest 
ornament.  More  than  any  other  element  in  the  landscape  it  is  in- 
dicative of  the  climate,  and  gives  to  every  part  of  the  globe  its  pecu- 
liar and  characteristic  aspect,     (leacher,  see  Note  page  122.) 

II.  _  VEGETATION   IN   DIFFERENT   LATITUDES. 

I.  Zones  of  Vegetation. 

Sunlight,  warmth,  and  moisture,  are  the  chief  climatic  conditions 


A    FOREST  ON  THE   ORINOCO. 


of  the  development  of  vegetable  life ;  hence,  corresponding  to  the 
climatic  zones,  there  are  well-defined  zones  of  vegetation,  the  bounda- 
ries of  which  are  approximately  indicated  by  isothermal  lines. 

In  high  latitudes,  however,  though  the  mean  annual  temperature 
is  below  the  freezing  point,  there  may  still  be  a  varied  vegetation, 
on  account  of  the  heat  of  the  summer. 

This  is  especially  the  case  in  the  northern  hemisphere,  where  the 
preponderance  of  land  augments  the  summer  heat,  while  it  keeps 
down  the  annual  average  by  intensifying  the  cold  of  winter. 

The  successive  zones,  from  the  poles  to  the  equator,  show  a  marked 

increase  in  the 
number  of  species, 
and  the  luxuriance 
of  growth,  of  the 
plants ;  with  suc- 
cessively higher 
types  in  those  which 
give  the  distinctive 
character  to  the 
vegetation  of  each 
zone. 

The  sunny  trop- 
ical regions,  which 
are  most  abund- 
antly provided 
with  warmth  and 
moisture,  display 
the  greatest  variety 
of  types,  and  the 
utmost  power  of 
vegetable  life. 
With  few  excep- 
tions, all  parts  of 
the  plant,  whether 
stem,  leaf,  flower,  or  fruit,  attain  their  greatest  development  here. 

II.  Northern  Cold  Zones. 

1.  The  North  Polar  Zone  has  a  mean  annual  temperature  of 
less  than  5°  Fahr.,  with  a  summer  from  four  to  six  weeks  in  length. 
This  region  is  almost  devoid  of  vegetation,  its  flora  consisting  only 
of  lichens,  and  a  few  diminutive  Alpine  plants  which  spring  up  and 
mature  during  the  short  summer. 

2.  The  Arctic  Zone,  which  may  properly  be  designated  the 
Zone  of  the  Mosses  and  Stunted  Trees,  has  a  mean  annual  temper- 
ature varying  from  5°  Fahr.,  in  the  north,  to  30°  in  the  south. 


180      Longitude      160       West  fro  m       14Q      Greenwich      12Q 


J  Region.    ' 

^   Tcj.ll    grass,        I  famj 


COLDl     TEMPERATE      ZONE    [mean    temper^     50°   to     40°  Fall*. 

REGIONS    OF    VEGETATION     IN    A    VERTICAL     DIRECTION    -    NEW    WORLD. 

NORTH     AMERICA  SOUTH     AMERICA 

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PATAOONIA 


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horizontal     -regions  in  the    rnap .         The    blu.c    peaks  are  covered  with  perpetual  snow. 


WOULD 

rilration  of 

FOREST  TREES 

inc.  i  pal 

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REGIONS      OF     VEGETATION     IN    A    VERTICAL      DIRECTION    -     OLD      WORLD. 


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100 


VEGETABLE   LIFE   IN   DIFFERENT   LATITUDES. 


The  vegetation  consists  of  but  a  few  species  of  plants,  and  these 
are  mostly  of  low  types,  mosses,  lichens,  sedges,  and  ferns,  being  the 
characteristic  forms.  Mossy  swamps,  called  tundras,  frozen  during 
the  greater  part  of  the  year,  occupy  a  considerable  portion  of  the 
lowlands  of  this  zone,  in  both  Europe  and  Asia. 

The  woody  plants,  —  which  include  some  varieties  of  willow  and 
birch,  azalea  and  rhododendron  —  in  general  trail  along  the  ground, 
rising  but  a  few  inches  above  it ;  while  the  main  stem,  sometimes 
several  feet  long,  is  hidden  among  the  mosses.  Stunted  trees  — 
dwarf  willow,  alder,  birch,  and  pine  —  are,  however,  found  near  the 
southern  limit  of  this  zone. 


III.  Cold-Temperate  Zone. 

In  the  Cold-temperate  Zone,  or  Zone  of  the  Conifers,  the 
mean  annual  temperature  is  from  30°  to  40°  Fahr.  This  zone  is 
characterized  especially  by  vast  forests  of  cone-bearing  trees,  with 
evergreen,  needle-shaped  foliage  ;  among  which  the  pine,  spruce,  and 
fir  are  the  predominant  forms. 

The  willow,  birch,  and  alder  occur  in  greater  numbers,  and  are 
of  finer  growth,  than  in  the  Arctic  Zone ;  and  the  ash,  the  aspen, 
and  the  larch  are  occasionally  found.  There  are,  also,  extensive  tree- 
less plains  which  are  covered  with  meadow  grasses  and  wild  varieties 
of  several  useful  plants,  including  flax,  Indian  rice,  and  oats. 

The  indigenous  fruits  are  mainly  acid  berries,  among  which  are 
the  currant,  cranberry,  raspberry,  and  strawberry.  The  most  hardy 
of  the  cereals  —  oats,  barley,  and  rye  —  and  the  potato,  the  turnip, 
and  some  other  edible  roots,  can  be  cultivated  with  success,  but  only 
in  the  more  favored  localities. 


IV.  The  Temperate  Zone. 

The  Temperate  Zone,  or  zone  of  Deciduous  Trees,  has  a  mean 
annual  temperature  varying  from  40°  to  60°  Fahr. 

The  forests — which  cover  vast  areas  in  North  America,  eastern 
Europe,  and  the  valleys  and  slopes  of  the  Altai  region  and  Manchu- 
ria, in  Asia  —  display  not  only  a  large  number  of  species  of  stately 
and  beautiful  trees,  but  also  a  rich  and  varied  undergrowth. 

Among  the  most  numerous  trees  are  the  oaks,  elms,  birches,  ma- 
ples, beeches,  walnuts,  and  chestnuts ;  with  the  ash,  larch,  linden, 
alder,  and  sycamore  —  all  of   which  lose  their  fobage  in  autumn. 

The  undergrowth  consists  chiefly  of  the  wild  apple,  yew,  holly, 
hawthorn,  wild  rose,  honeysuckle,  clematis,  azalea,  and  rhododen- 
dron ;  varied  by  the  wild  grape,  and  some  other  climbing  plants. 

The  herbaceous  vegetation  embraces  nearly  all  those  families  of 
plants  which  furnish  the  staple  articles  of  food  among  civilized  na- 
tions (see  page  111,  Topic  II.  3)  ;  together  with  a  great  variety  of 
meadow  grasses,  and  the  hemp,  flax,  and  tobacco. 

The  most  numerous  of  the  other  characteristic  orders,  are  the  um- 
belliferous plants,  as  the  parsnip,  carrot,  and  caraway  ;  the  cichora- 
ceae,  as  the  lettuce  and  dandelion  ;  and  the  cruciferae,  including  the 
cabbage,  turnip,  radish,  mustard,  etc.  The  cruciferae,  which  are 
almost  confined  to  the  northern  hemisphere,  are  so  numerous  and 
varied  as  to  give  a  distinctive  character  to  the  herbaceous  flora  of 
the  temperate  zone,  especially  in  Europe. 

Exceptions  to  the  general  abundance  of  vegetation  in  the  temperate  zone  are 
found  in  the  high  barren  plains  and  plateaus  of  western  North  America ;  the 
steppes  of  southeastern  Europe,  and  of  western  Asia ;  and  the  deserts  of  Gobi 
and  Shamo,  in  eastern  Asia.     (See  pages  24,  II.  3.  and  25;  also  101.) 


V.  Warm-Temperate  Zone. 

The  Warm-temperate  Zone,  or  Zone  of  Winter  Foliage,  situ- 
ated a  little  north  of  the  Tropic  of  Cancer,  has  a  mean  annual  tem- 
perature varying  from  60°  to  72°  Fahr. 

Its  characteristic  vegetation  consists  of  trees  and  shrubs  which  re- 
tain their  foliage  throughout  the  year,  though  their  growth  is  inter- 
rupted during  the  winter.  The  leaves  are  in  general  tough,  stiff, 
and  glossy ;  but  lack  the  delicate  tints  which  adorn  the  foliage  of 
the  deciduous  trees  in  spring  and  summer,  and  the  more  gorgeous 
hues  of  autumn. 

Here  are  found  the  live-oak,  myrtle,  laurel,  and  oleander,  and 
the  box,  invaluable  in  the  arts ;  with  the  cotton,  the  mulberry  and 
the  olive  ;  and  tea,  rice,  and  millet.  Delicate  fruits  also  abound,  in- 
cluding the  fig,  orange,  lemon,  pomegranate,  and  almond  —  all  char- 
acteristic of  this  region  —  and  the  choicest  varieties  of  the  vine. 

VI.  Tropical  Zone. 

The  Tropical  Zone,  or  Zone  of  Palms  and  Bananas,  has  a 
mean  annual  temperature  varying  from  72°  to  82°  Fahr.  The  veg- 
etation embraces  an  immense  variety  of  species,  in  general  remark- 
able for  luxuriance  of  growth  and  great  development  of  foliage. 
(See  illustration,  page  97.) 

The  ferns,  which  in  other  zones  are  small  herbaceous  plants,  here 
assume  the  proportion  of  trees,  rivaling  the  palms  in  the  beauty  of 
their  crown  of  foliage ;  and  the  grasses  far  surpass  those  of  middle 
latitudes  in  growth.  To  the  latter  class  belongs  the  invaluable 
sugar-cane,  and  the  gigantic  bamboo  which  attains  the  height  of  60 
feet  or  more,  while  its  hollow  stalk  furnishes  the  principal  building 
material  used  in  the  East  Indian  Archipelago. 

One  of  the  most  striking  characteristics  of  the  tropical  forests  is 
the  great  variety  of  trees  which  are  mingled  together,  without  the 
preponderance  of  any  one  family ;  while  in  temperate  climes,  ex- 
tensive forests  of  a  single  family  —  as  of  pine,  oak,  beech,  etc.  —  are 
common.  Another  distinguishing  feature  is  the  number  of  large 
flowering  trees.  The  plants  are  perpetually  covered  with  verdure, 
and  many  yield  a  constant  succession  of  fruits  and  flowers. 

The  food  producing  plants,  indigenous  to  this  zone,  include  the 
date,  the  sago,  and  the  cocoa  palm ;  the  bread  fruit  and  the  cow- 
tree  ;  the  plantain  or  banana ;  rice,  and  the  sweet  potato,  yam,  arum, 
and  manioc. 

The  caoutchouch  and  gutta-percha,  extensively  employed  in  manufactures ;  the 
rosewood,  mahogany,  and  ebony,  so  valuable  in  the  arts  for  their  rich  color  and 
the  fine  polish  they  are  capable  of  receiving ;  with  the  cotton,  coffee,  and  a  multi- 
tude of  other  useful  plants,  are  all  natives  of  the  tropical  zone. 


VII.  Southern  Zones. 

1.  The  Warm  Temperate  Zone  resembles  the  corresponding 
zone  north  of  the  Equator,  with  the  exception  that  it  has  few  native 
food  plants.  The  limited  supply  of  moisture  in  Australia  and  South 
Africa,  gives  a  peculiar  meagreness  to  the  general  aspect  of  the  veg- 
etable world  in  those  regions,  which  is,  however,  relieved  to  a  certain 
extent  by  the  brilliancy  of  the  flowers.     (Pages  104,  105.) 

2.  The  Temperate  and  Cold-Temperate  Zones,  though 
having  a  higher  average  temperature  than  the  corresponding  regions 
of  the  north,  show  less  luxuriance  and  variety  of  vegetation. 

The  former  is  characterized  by  forests  of  beech,  and  of  the  arau- 
caria,  which  takes  the  place  of  the  northern  pines  ;  but  the  latter 
has  only  the  flora  of  the  Arctic  zone. 


VEGETATION  IN  THE  NORTHERN  CONTINENTS. 


101 


III.  — VEGETATION  IN  THE  NORTHERN  CONTINENTS. 

I.  Similarity. 

In  the  Arctic  zone  the  vegetation  is  almost  identical  throughout 
the  three  continents,  and  they  show  a  marked  similarity  in  the  cold- 
temperate  zone.  Advancing  southward  an  increasing  diversity  is 
apparent,  until,  in  the  warm  and  tropical  zones,  the  flora  of  each 
continent  possesses  a  distinctive  character. 

II.  Xorth  America. 

1.  Temperate  and  Warm  Regions.  In  the  temperate  region, 
this  continent  is  distinguished  from  Asia  and  Europe,  especially  by 
the  greater  variety  of  its  forest  trees ;  and  in  the  warm,  by  the 
number  of  large  flowering  trees.  The  most  striking  of  these  are  the 
tulip-tree,  the  magnolias,  the  catalpas,  and  the  locusts. 

The  arid  plateaus  of  the  warm  zone  are  covered  with  thickets  of  the  cactus, 
a  family  of  plants  peculiar  to  America;  the  yucca,  a  plant  of  the  lily  family;  the 
agave  or  American  aloe  (century  plant) ;  and  the  mesquite,  a  sort  of  locust. 

The  distribution  of  forests,  fertile  prairies,  and  sterile  plains,  in  the  temperate 
and  warm  zones  of  this  continent,  is  shown  in  the  map,  Vegetation  of  the  United 
Slates,  on  page  1 20,  which  gives  also  the  staple  articles  of  culture  in  the  latter  zone. 

2.  The  TROPICAL  REGION  is  like  South  America  in  the  luxuri- 
ance and  variety  of  its  flora,  with  nearly  the  same  kinds  both  of 
trees  and  of  herbaceous  plants.     (Page  104,  II.  2.) 

III.  Asia-Europe. 

1.  Western  Asia  and  Europe  are  distinguished  by  the  remark- 
able similarity  of  their  flora,  and  the  great  variety  of  useful  or 
beautiful  plants  which  are  indigenous. 

The  cork-oak,  and  the  box ;  the  mint,  thyme,  lavender,  and  other 
aromatic  herbs ;  the  gladiolus,  iris,  narcissus,  carnation,  and  migno- 
nette, are  all  indigenous  to  southern  Europe. 

The  oleander,  syringa,  almond,  and  fine  varieties  of  the  cherry, 
are  natives  of  Asia  Minor ;  the  peach,  melon,  cucumber,  and  hya- 
cinth, of  Persia ;  the  choicest  varieties  of  the  vine  and  apricot,  of 
Armenia  j  and  the  date-palm,  fig,  olive,  mulberry,  and  damask-rose, 
of  Syria.     All  of  these  are  now  naturalized  in  southern  Europe. 

2.  The  ARID  table  lands  of  Iran  and  Mongolia,  produce  only 
thorny  bushes,  or  stunted  and  almost  leafless  trees,  and  a  few  species 
of  herbaceous  plants,  which  afford  sustenance  for  the  herds  of  the 
nomadic  inhabitants. 

Thibet,  being  both  dry  and  cold,  has,  except  in  certain  favored 
spots,  the  flora  of  the  cold-temperate  and  Arctic  zones.     Furze  and 


other  prickly  shrubs,  with  the  gooseberry,  currant,  hyssop,  rhubarb, 
lucern,  and  assafoetida,  are  the  most  common  plants  ;  but  two  or 
three  species  of  wheat,  of  buckwheat,  and  of  barley,  are  indigenous 
in  this  table-land. 

3.  China  is  the  home  of  the  camphor  laurel  and  the  paper  mul- 
berry ;  of  the  tea  plant,  which  abounds  both  in  that  country  and  in 
Japan  ;  of  some  species  of  cotton  ;  and  of  the  sugar-producing  sor- 
ghum. 

4.  India,  Indo-China,  and  the  Indian  Archipelago,  disjxlay, 
in  the  lowlands,  all  the  luxuriance  and  variety  of  vegetation  which 
belongs  to  the  tropical  zone  ;  while  in  the  more  elevated  regions  the 
trees,  shrubs,  and  herbaceous  plants  of  the  warm-temperate  and  tem- 
perate zones  abound.     (See  page  102,  Himalaya  Mountains, .) 

(1.)  Characteristics.  Along  the  coasts  are  thickets  of  mangroves, 
and  a  matted  vegetation  of  forest  trees,  bamboos,  coarse  grasses,  and 
creeping  and  climbing  plants.  The  trees  are  covered  with  parasites, 
or  air  plants,  of  almost  infinite  variety,  one  of  which,  the  rafflesia,  a 
yard  in  diameter,  is  the  largest  flower  known. 

Palms  are  especially  numerous,  and  occur  in  a  great  variety  of  spe- 
cies, some  of  which  bear  the  largest  leaves  known.  The  banyan  fig, 
and  kindred  species,  abound,  especially  in  India.  These  remarkable 
plants  send  down  shoots  from  the  branches,  which  take  root  and  be- 
come new  trunks,  so  that  a  single  tree  often  produces  a  large  grove. 

(2.)  Useful  Plants.  The  teak,  one  of  the  most  valuable  of  tim- 
ber trees  ;  the  gutta-percha,  camphor,  sandal-wood,  and  ebony ;  the 
true  indigo,  now  naturalized  throughout  the  tropical  zone  ;  and  a 
great  variety  of  trees  yielding  dyes,  spices,  gums,  and  resins,  are  na- 
tives of  this  region.  The  spices,  which  are  more  especially  charac- 
teristic of  the  islands,  include  the  nutmeg,  clove,  cinnamon,  cassia, 
ginger,  and  black  pepper,  the  last  being  peculiar  to  the  hottest  por- 
tions of  the  archipelago. 

No  part  of  the  earth  surpasses  this  region  in  the  number  of  its  na- 
tive fruits  and  esculent  vegetables.  Among  these  are  the  bread- 
fruit, orange,  mango,  mangosteen,  banana,  cocoa-nut,  sweet  potato, 
arum,  and  yam  ;  and  different  varieties  of  the  cucumber,  melon,  and 
gourd  family.     The  sago  palm  is  also  a  native  of  the  Archipelago. 

5.  Arabia.  In  the  vast  deserts  of  the  interior,  mimosas,  and 
stunted  prickly  bushes  which  appear  here  and  there  in  the  sand, 
form  the  only  vegetation  ;  but  the  date  palm  abounds  on  the  oases. 

In  the  mountains  and  valleys  of  the  south  and  east  are  many 
varieties  of  the  acacia,  from  one  of  which  the  gum  arabic  of  com- 
merce is  obtained.  Several  species  of  trees  and  shrubs  also  yield 
fragrant  balsams  or  resins,  the  odoriferous  plants  giving  the  especial 
character  to  the  Arabian  flora. 


QUESTIONS   ON   THE   MAP   OF   VEGETATION.    (Pages  98,  99.) 


Name  the  several  zones  of  vegetation.  In  what  continent  is  the  tropical  zone  broadest? 
What  parts  of  the  New  World  are  included  in  this  zone?  What  parts  of  the  Old  World? 
What  plants  ar«  especially  characteristic  »f  the  tropical  zone? 

What  are  the  principal  coffee  districts  of  the  New  World?    Of  the  Old  World? 

In  which  of  these  is  coffee  native  ?  Where  is  the  principal  spice  district  ?  Where  is  the 
chief  district  of  rice  cultivation?  Where  is  the  principal  cotton  region  of  the  Old  World?  In 
what  zone  are  the  principal  cotton  and  rice  districts  of  North  America?  Are  these  plants  native 
or  introduced  in  this  region  ? 

What  forme  the  characteristic  vegetation  of  the  warm-temperate  zone? 

What  part  of  the  New  World  it  included  in  the  northern  warm-temperate  zone?  What 
parts  of  the  Old  World  ? 

What  trees  mark  this  zone  in  the  eastern  part  of  the  United  States?  What  plants  are  charac- 
teristic of  the  high  western  plateaus? 

Name  the  principal  plants  of  this  zone  in  Europe :  in  Africa;  in  western  Asia;  in  eastern  Asia. 

What  plant  is  especially  characteristic  of  the  eastern  portion  of  China? 

What  part  of  North  America  is  included  in  the  temperate  zone  ?  rn  what  part  of  the  conti- 
nent is  this  zone  broadest  ?     In  which  continent  does  it  lie  farthest  north  ? 


What  is  the  characteristic  vegetation  of  the  temperate  zone?  What  extensive  desert  lies  in 
this  zone?  What  is  the  vegetation  of  eastern  Asia  in  this  zone?  Of  central  and  western 
Asia  ?    Of  Europe  ? 

What  trees  characterize  temperate  America  east  of  the  Rocky  Mountains?  What  trees  grow 
on  the  Sierra  Nevada  and  Cascade  Mountains?  Where  are  the  only  barren  regions  of  North 
America?     Where  is  the  principal  region  of  tobacco  culture? 

Where  is  the  cold-temperate  zone  situated  farthest  north?  What  part  of  North  America  is 
included  in  it?  Of  Europe?  Of  Asia?  What  is  the  characteristic  vegetation  of  this  zone ? 
What  trees  form  the  most  extensive  forests  in  this  zone  in  North  America?  In  Europe?  In 
Asia  ? 

What  regions  are  included  in  the  warm-temperate  zone  of  the  southern  hemisphere? 

What  is  the  characteristic  vegetation  of  this  zone?  What  lands  are  included  in  the  south- 
em  temperate  zone?     What  are  the  characteristics  of  this  zone? 

What  lands  are  included  in  the  southern  cold-temperate  zone?  What  is  the  characteristic 
vegetation  of  this  zone? 

How  do  these  southern  zones  compare  in  mean  temperature  with  the  northern  ?  How  do  they 
compare  in  luxuriance  and  variety  of  vegetation?     In  useful  plants? 


)000  Eng.Feet. 


ANII.K8 


HIMALAYA 


Nevada  de  Soram.Bolrwa.  15.000  Tt.  I.aLJ5"4B'S. 

IIIimuiii.no I.  24,200  Ft.l.iO-4.0'.S. 

(himbornro,  Ecuador.  21422  Ft.L.l'  2IS. 

Anli.sana,£cuador.   19,137  Ft.L.O'36'S. 

Lul.l9*N. 


Soda. 

Lichens 
Alpine 

Plants. 
Grasses. 
Shrubs. 
He/ana. 

jallorua. 

Oak. 
CineheatA 
Vvrrgreens\ 
irith  ffrick 

JirtUTrfa. 
Mrrth 

ferns, 
figs . 

Hanarjas\ 
Palms 


Popocatepetl,  17,784  Fl. 

0ri-/.«bu,17,0»4.  Ft. 


Mt.Kverest,N?pa  1 .29.002  FLL2S 


J)um  Huy,Cashmere.2.3,407  Ft. 
L.MH. 


njingH.. ','>',. 


Regions. 


Alpine 
Plants. 
Grasses. 

WkslfPuie.] 

Oak. 

Alder. 

Pines. 

Agave 

liuea 
live  Oak.  J.D 
Magnolia* 
Lrnwels. 

Mimosas. 
Tree  firms. 
Jianaiws. 
Palms. 


'Alpine  Plants. 

Wwdadendnm 

Ash 

Juniper. 

Birch. 

Oak. 

P'nQ/J>eodaiu>  \ 
Deezdruous 
Trees . 
^Jhne,  fNeozu) 
Lonu  leaved 
Pine.  Oak. 
Matfaolia. 
Laurels.  Piys. 
I     t~Hananas . 
K     Palms, 
u'erai .  Junglt 


UK 


WARM     TEMPEHATK    »OXK. 


IV.  —  VEGETATION   AT    DIFFERENT  ALTITUDES. 


I.  Vertical  Zones  of  Vegetation. 

In  consequence  of  the  diminution  of  the  temperature  with  in- 
creasing altitude  (see  page  72,  Topic  II.,  2),  vertical  zones  of  veg- 
etation may  be  distinguished,  with  characteristics  no  less  marked 
than  those  of  the  horizontal  zones.  The  observer,  passing  from 
the  base  to  the  summit  of  high  mountains,  in  any  latitude,  finds 
variations  in  the  character  of  the  plants  similar  to,  though  not  iden- 
tical with,  those  observed  in  advancing  to  higher  latitudes. 

The  above  diagram  is  designed  to  furnish  a  graphic  representation  of  the  verti- 
cal distribution  of  vegetation  in  the  different  latitudes.  The  Andes  serve  as  the 
type  for  mountains  in  the  tropical  zone ;  the  Himalayas,  for  those  in  the  warm- 
temperate  ;  the  Alps,  for  those  in  the  temperate  proper ;  and  the  Scandinavian 
Alps  for  the  mountains  of  the  cold-temperate  zone. 


II.  The  Andes  and  Mexican  Mountains. 

1.  Tropical  Region.  Below  4,000  feet  of  altitude,  the  vege- 
tation on  the  slopes  of  the  Andes  consists  of  families  of  plants 
belonging  to  the  tropical  zone ;  and  displays  the  luxuriance  of 
growth,  the  abundance  of  foliage,  and  the  immense  variety  of  spe- 
cies which  is  especially  characteristic  of  tropical  America.  In  the 
lower  half  of  this  region,  the  palms  and  the  various  species  of  the 
banana  are  the  dominant  types ;  in  the  upper  half,  the  tree-ferns 
and  the  fig  family,  are  the  most  numerous  and  characteristic  trees. 

2.  Warm  Region.  Between  4,000  and  8,000  feet  the  vegeta- 
tion is  that  of  the  warm-temperate  zone  of  the  New  World  ;  and  is 
characterized  by  its  thick,  lustrous,  evergreen  foliage.  The  laurel, 
myrtle,  evergreen-oak,  and  magnolia,  among  trees  ;  and  the  agave, 
yucca,  and  cactus,  among  herbaceous  plants,  give  to  this  region  its 
distinctive  character. 

3.  Temperate  Region.  From  8,000  to  10,000  feet  those  fami- 
lies of  trees  occur  which  comnose  the  deciduous  forests  of  the  tem- 


VERTICAL    DISTRIBUTION    OF 

perate  zone  ;  but  the  character  of  the  species  is  modified  by  that  uni- 
formity of  temperature  throughout  the  year  which  distinguishes  the 
tropical  zone  at  every  altitude.  In  this  region,  and  in  the  upper 
part  of  the  preceding,  grows  the  cinchona,  so  highly  valued  for  the 
quinine  and  other  remedies  obtained  from  it. 

4.  Cold  Region.  Above  10,000  feet  of  altitude  we  find  only 
the  vegetation  belonging  to  the  .cold-temperate,  arctic,  and  polar 
zones.  Dwarf  trees  and  shrubs,  grasses,  and  alpine  flowering  plants, 
occur  in  succession ;  and  are  followed  by  a  region  where  only  lich- 
ens grow  upon  the  naked  rock,  above  which  are  the  fields  of  perpet- 
ual snow. 

In  the  Andes  of  Bolivia,  where  the  snow  fine  is  higher  than 
under  the  Equator,  these  several  zones  each  extend  a  little  higher 
than  in  the  Equatorial  Andes.  On  the  mountains  of  Mexico,  the 
same  succession  of  zones,  and  similar  species  of  plants,  are  gen- 
erally found.  There  is,  however,  an  exception  in  the  third,  or 
temperate  region,  where  the  western  pine  abounds  ;  and  the  Alpine 
vegetation  reaches  the  snow  line. 


III.  The  Himalayas. 

1.  Tropical  Region.  These  mountains  are  situated  on  the 
southern  boundary  of  the  warm-temperate  zone.  On  their  southern 
slope,  which  is  completely  sheltered  from  polar  winds,  they  have  a 
narrow  belt  of  tropical  vegetation.  It  extends  to  the  altitude  of 
2,000  feet  in  the  northwest,  and  4,000  feet  in  the  southeast ;  and  is 
marked  by  the  various  species  of  plants  belonging  to  the  flora  of 
India.  The  palms,  bananas,  figs,  and  bamboos  grow  here  with 
scarcely  less  luxuriance  than  in  the  lowlands. 

At  the  foot  of  the  mountains  is  a  narrow  belt  of  marshy  jungle,  known  as  the 
Terai,  covered  with  an  almost  impenetrable  tangle  of  tropical  vegetation,  and  unin- 
habitable by  reason  of  its  malarious  climate. 

2.  The  warm  region  extends  to  the  altitude  of  7,000  or  8,000 
feet,  and  is  characterized  by  those  families  of  plants  which  occur 
throughout  the  warm-temperate  zone  of   the  northern  hemisphere. 


30,000    English  Feet. 


J66KU.ii8'n'7<. 


AIjPS     and     pvrknees. 


Mt.Hlunc.Savoy  15,780  Ft . 
I.. 45"  30'N. 


H>g/ons 


Mte.«osa,SwitzerH  15.223 Ft. L.45'  OTN. 


* 


I!! 


tint  Ptonfjr\ 

uvftKtrm/n'ri. 
Shrub  a 
»*«/«/ IW/W 
Hinli  A.tl, 
.ihmii. 

Cnnitrrs 
Spmtt'Ilinh 

^flur.WUtm: 

VmtaJem/nn^      UfyinrHunts. 

^\WlCtlottfudrflii. 

J     ('fnt/pnf. 
^/fcv/:  fir.  fyrutf 

yieriJ i*ous7rtv*\ 
TMiglmmlKuA  ^HlrclUs/l.OilJt. 
Bamhra.,.      U  Chemnt. 

Palm*  VPiTuwMyiilr 

Terai.  Vhir. 


'hkMagiioiw. 

Walnut, 
'jliiret  flitvntit 

ffnt/ijft*. 


Pic  Anethou, Spain. 11.108  Ft. 
L.  W38KT. 

Mt.Pwrdu,  Sp  10,994  Ft. 
L.42'40'N. 


SCANDINAVIAN       ALPS. 

YbUM,  Norway.  8442  Ft.I.OIMON. 

Sneeliattiiii.  Norway  1. TOT  FtL62'20rN. 


n/te/'lunts.     ] 
fwurt'Jitaiiw.  >1V 
Srolrfi  fir. — ■, 

S/inirf/ir     )J^llpine  Hunt. 


— \  V\Thn/ifHirrfl. 


Yew. 
Jleenh 
OnkBea^ifr\    J  (m/ifrix. 


(lirtmiil 
t-htr. 


fiirrli. 

(i'//i/ri 

I'iites . 

Fir.?. 


TKHPKHATK     KO.VK 


fSsPfflii 


COI.I)     TEMFER.VTK     y.ONK. 


£M 


I1'4 

ys 
In 

1)6 

yi4 
In 


jio 
Sulifrlma, Lapland  6177  Ft . 

L.67*lu'N.  _|8 


wg^Hpinr  limits.     | 

fiirrh.  —K 
Co/ii/fT*.    \l 


NTS    IN    VARIOUS    LATITUDES. 

The  oaks,  especially,  of  which  twenty-five  species  grow  here,  attain 
great  size.  The  long-leaved  pine,  which  is  characteristic  of  the 
Himalayas,  also  grows  luxuriantly. 

3.  Temperate  Region.  Above  the  warm  region,  extending  to 
an  altitude  of  11,000  or  12,000  feet,  there  is  a  belt  of  deciduous 
trees,  mingled  with  pines,  cedars,  and  other  conifers.  All  the 
plants  are  closely  allied  to  those  which  characterize  the  temperate 
zone  of  both  Asia-Europe  and  North  America.  The  poplar,  willow, 
maple,  alder,  ash,  and  birch  are  all  abundant  here  ;  and  rhododen- 
drons grow  in  great  variety  and  beauty. 

4.  Cold  Regions.  Above  the  last,  reaching,  to  the  height  of 
from  14,000  to  16,000  feet,  is  a  region  corresponding  to  the  Arctic 
zone,  where  the  vegetation  consists  of  dwarf  trees,  stunted  shrubs, 
and  grasses.  These  are  succeeded  by  small,  bright  flowering  Alpine 
plants,  which  extend  to  the  line  of  perpetual  snows. 


IV.  The  Alps  and  Pyrenees. 

1.  Warm  Region.  These  mountains,  situated  on  the  southern 
boundary  of  the  temperate  zone,  have,  upon  their  southern  slopes, 
a  narrow  belt  of  vegetation  belonging  to  the  warm-temperate  zone. 
It  is  characterized  by  the  fig  and  the  olive,  which  do  not,  however, 
extend  above  the  altitude  of  500  feet. 

2.  Temperate  Region.  In  this  region,  extending  to  the  alti- 
tude of  2,500  feet,  there  is  a  belt  of  deciduous  trees,  —  character- 
ized by  the  chestnut  and  oak,  and  the  vineyards,  so  numerous  in 
Switzerland  —  succeeded  by  conifers,  which  extend  to  about  6,000 
feet  Both  belts  are  more  strongly  marked  than  in  the  Himalayas, 
where  the  deciduous  trees  and  conifers  are  largely  intermingled. 

3.  Cold  Region.  The  conifers  are  succeeded  by  rhododendrons, 
and  diminutive  Alpine  plants,  extending  to  the  height  of  9,000  feet ; 
beyond  which  are  the  perpetual  snows.  This  Alpine  flora  is  marked 
especially   by  very  short  stems,  brilliant  flowers,  and  large  roots. 

to  the  warmth  of  the  summer,  these  mountains  and  the  Himalayas  show, 
|  rge  of  the  perpetual  snows,  a  much  richer  flora,  both  in  number  of  species 


I 


ami  beauty  of  forms  and  colors,  than  the  corresponding  region  of  the  Anues, 
where  the  uniformity  of  temperature  throughout  the  year  limits  the  vegetation  to  a 
few  varieties  of  plants  which  are  mostly  of  low  types. 


V.  The  Scandinavian  Alps. 

These  mountains,  situated  in  the  cold-temperate  zone,  show  only 
a  region  of  conifers  and  birches,  succeeded  by  a  belt  of  dwarf  shrubs 
and  Alpine  plants,  the  characteristic  flora  of  the  Arctic  zone.  In 
the  south  the  conifers  extend  to  about  2,800  feet,  the  birches  to 
3,500 ;  but  the  altitude  to  which  they  grow  diminishes  rapidly  to- 
wards the  north. 


VI.  Cultivated  Plants. 

The  limits  of  the  various  species  of  cultivated  plants,  in  the  dif- 
ferent regions  indicated  above,  are  no  less  marked  than  those  of  the 
spontaneous  vegetation.  They  furnish  a  striking  illustration  of  the 
advantage  of  the  varying  seasons  of  the  warm  temperate  zone  over 
the  uniformity  of  the  tropical. 

On  the  Andes  and  the  Mexican  mountains,  from  latitude  16°  south 
to  19°  north,  the  average  upper  limit  of  the  culture  of  the  cereal 
grains  and  the  potato,  is  about  10,000  feet ;  but  in  the  plateau  of 
Bolivia,  maize  will  mature  somewhat  higher,  and  barley  as  high  as 
13,000  feet  above  the  sea  level,     k 

In  the  Himalayas,  between  28°  and  34°  north  latitude,  lye  and 
barley  are  successfully  cultivated  at  the  altitude  of  14,000  feet,  and 
wheat  at  12,000  ;  while  turnips  and  some  other  edible  roots  succeed 
as  high  as  16,000  feet. 

In  the  Alps  and  the  Pyrenees,  latitudes  42°  to  45°  north,  the  cul- 
ture of  the  cereals  terminates  at  from  4,000  to  6,000  feet  of  alti- 
titude.  In  the  Scandinavian  Alps,  in  latitudes  61°  to  67°,  barley 
and  oats  grow  only  near  the  sea  level ;  though  rye  may  succeed  as 
high  as  600  feet  above  the  sea. 


104 


VEGETATION   OF  THE   SOUTHERN   CONTINENTS. 


V.— VEGETATION  OF  THE  SOUTHERN  CONTINENTS. 

I.  Africa. 

1.  Equatorial  Africa.  Africa,  the  dryest  of  the  tropical  con- 
tinents, and  the  hottest  of  all,  has,  in  a  large  portion  of  its  area,  a 
comparatively  meagre  flora. 

Equatorial  Africa,  however,  from  about  15°  north  latitude  to  20° 
south,  has  a  luxuriant  vegetation,  with  a  general  resemblance  in 
types  to  those  of  India  ;  yet,  even  in  this  most  favored  zone  of  the 
continent,  we  nowhere  find  such  dense,  interminable  forests,  as  char- 
acterize tropical  America.  The  wooded  lands,  though  extensive,  are 
separated  by  large  treeless  tracts,  which  are  covered  with  tall  sedges, 
and  gigantic  grasses  with  branching  stems. 

On  the  borders  of  this  equatorial  region,  groves  of  acacias,  mimo- 
sas and  cassias,  and  stunted  bushes,  form  a  transition  to  the  arid, 
treeless  plateaus  of  South  Africa  and  the  deserts  of  Sahara. 

Palms  are  numerous,  __^_^^_^^^^^^^^^^^^^^^^^^^^^^^^^^ 
but  are  of  less  varied 
species  than  in  other 
tropical  lands.  The 
doom-palm,  remarkable 
as  being  the  only  spe- 
cies with  a  branching 
stem  (see  illustration), 
is  peculiar  to  the  basin 
of  the  Nile,  where  it  is 
accompanied  by  the 
wine-palm  with  its  long 
flower  clusters,  and  the 
deleb-palm  with  its  sin- 
gularly swollen  trunk. 
The  oil-palm  is  found 
only  on  the  coasts  of 
the  Gulf  of  Guinea. 

The  musanga,  kin- 
dred to  the  bread-fruit 
of  the  East  Indies,  and 
the  yam  tribe,  are 
plentiful  throughout 
equatorial  Africa;  and 
coffee  is  indigenous  in 
the  plateau  of  Abys- 
sinia. 

The  alluvial  plains 
on  the  western  coast 
are  covered  with  thick- 
ets of  mangroves  and  other  trees,  intermingled  with  many  poisonous  plants.  On 
the  higher  lands  are  groves  of  the  baobab,  a  remarkable  tree,  which,  though  rarely 
more  than  fifty  or  sixty  feet  high,  has  a  trunk  sometimes  over  thirty  feet  in  diame- 
ter. Solitary  pandanus  trees  rise  here  and  there  ;  and  the  butter  tree,  peculiar  to 
Africa,  abounds.  The  tamarind,  a  flowering  tree  similar  to  the  locust,  and  valu- 
able for  its  timber,  grows  throughout  equatorial  Africa. 

2.  Northern  Africa.  The  Mediterranean  region  of  Africa 
bears  a  marked  resemblance  to  southern  Europe,  more  than  half  the 
plants  which  compose  the  flora  of  the  former  being  found  in  the 
latter. 

South  of  the  Atlas  region,  and  upon  the  oases  in  the  midst  of  the 
desert,  are  extensive  groves  of  the  date-palm  which  furnishes  a  large 
part  of  the  food  of  the  inhabitants  of  the  country. 

The  plants  of  the  Sahara  are  few,  and  consist  mainly  of  prickly 
and  thorny  bushes,  and  stunted  shrubs,  of  the  same  general  charac- 
ter as  those  of  Arabia ;  yet  some  portions  yield  a  harsh,  prickly 
grass,  valuable  as  food  for  the  camel. 

3.  South  Africa.  The  flora  of  the  high,  arid,  southern  part  of 
Africa  differs  entirely  from  that  of  other  portions  of  the  continent ; 


CHARACTERISTIC  PLANTS   OF    AFRICA. 


and  includes  an  immense  number  of  species,  many  of  which  produce 
flowers  of  the  most  gorgeous  hues. 

Thorny  and  prickly  shrubs  with  meagre  foliage,  and  fleshy  and 
succulent  plants,  are  the  most  numerous  types.  The  latter  include 
the  house-leek  tribe,  the  mesembryanthems,  and  the  leafless  euphor- 
bias which  correspond  to  the  cactus  family  of  the  New  World.  (See 
illustration  below.) 

The  flowering  plants  include  300  different  species  of  heaths,  and  over  200  pro- 
teas,  both  of  which  are  distinguished  by  their  small,  narrow,  leathery,  evergreen 
leaves,  and  their  large  clusters  of  brilliant  flowers.  Aloes,  in  great  variety,  grow 
in  thickets  which  form  the  so-called  "  bush  "  of  South  Africa.  Many  beautiful 
plants  of  the  oxalis  or  wood-sorrel  tribe  are  found  here ;  with  nearly  every  known 
species  of  gladiolus,  and  a  great  number  of  geraniums  (Pelargonium). 

In  the  dry  season  the  high  interior  plateaus  have  almost  the  aspect  of  a  desert, 
bearing  only  a  few  stunted  shrubs,  with  some  succulent  plants  and  mimosas  along 
the  borders  of  the  streams.  Immediately  on  the  commencement  of  the  rainy  sea- 
son, however,  the  germs,  bulbs,  and  roots,  which  have  lain  dormant  in  the  parched 
soil,  send  forth  their  shoots,  and  the  country  is  quickly  covered  with  a  brilliant 
and  varied  vegetation. 


II.  South  America. 

1.  General 
Character.  The 
wealth  of  moisture 
which  characterizes 
the  continent  of 
South  America,  to- 
gether  with  its 
tropical  tempera- 
ture, secures  to  it  a 
vegetation  unsur- 
passed in  luxuri- 
ance of  growth. 
The  e sp ecial 
characteristics  of  the 
South  American 
llora  are,  its  gfeat 
variety  of  species 
and  remarkable  de- 
velopment of  foli- 
age ;  and  the  bril- 
liancy of  its  blos- 
soms, with  the  great  number  of  large  flowering  trees. 

2.  Forests  within  the  Tropics.  Among  the  most  numerous 
plants  are  the  palms  and  bananas,  the  tree  ferns,  the  fig  family  — 
the  kindred  of  the  banyan  tree  —  and  the  mimosas. 

Reeds  and  grasses  of  great  height,  and  a  multitude  of  herbaceous 
flowering  plants,  including  the  beautiful  Victoria  Regia  (see  illus- 
tration, page  97),  enrich  the  flora,  especially  in  the  vicinity  of  the 
streams.  Passion-flowers,  and  other  slender  creepers,  twine  round 
the  lower  plants  ;  while  other  vines,  often  as  thick  as  cables,  climb 
the  trees,  and  stretch  from  bough  to  bough,  intermixed  with  a  mul- 
titude of  parasitic  plants,  bearing  the  most  brilliant  flowers. 

This  richness  of  vegetation,  which  finds  its  parallel  nowhere,  ex- 
cept in  a  comparatively  small  portion  of  Asia,  extends  over  the  larger 
part  of  the  continent  of  South  America,  and  the  lowlands  in  the 
tropical  portions  of  North  America.  It  characterizes  especially  the 
plains  of  the  Amazon  basin,  and  the  adjacent  portions  of  the  Orinoco 
and  La  Plata  basins. 

Included  in  this  tropical  flora  are  the  mahogany,  rosewood,  and  other   trees  fur 


Date  Palm.  IXkb  Palm. 

Euphorbia. 


Tamarind.        Wine  Palm. 
.Mcht-mbry  anthem. 


;c. 
ert 


VEGETATION  OF   THE   SOUTHERN   CONTINENTS. 


105 


nishing  valuable  timber  or  dyes ;  the  invaluable  caoutchouc ;  the  coca  of  the 
Andes,  whose  leaf  possesses  powerful  stimulant  and  narcotic  properties ;  the  to- 
bacco, and  the  capsicum,  or  red  pepper ;  the  cinchona,  and  many  other  medicinal 
plants ;  and  a  great  variety  of  plants  yielding  food,  perfumes,  balsams,  gums,  and 
resins. 

Among  the  esculent  productions  are  the  yam,  whose  large  tuber  replaces  the 
Dotato  in  hot  climates ;  the  cassava,  from  the  root  of  the  manioc  :  the  fruits  of  the 
Bcrtholletia, —  known  in  commerce  as  the  "Brazil-nut";  the  milky  juice  of  the 
cow-tree  ;  the  delicious  cherimoya  and  pine-apple ;  the  fruit  of  the  cacao  tree, 
from  which  chocolate  is  prepared ;  the  vanilla,  so  valued  for  its  perfume  ;  and  the 
algaroba  bean,  the  fruit  of  a  kind  of  acacia.  The  yerba-mate,  a  species  of  holly, 
the  leaves  of  which  are  used  as  tea,  is  a  native  of  the  Paraguay  basin. 

3.  Exceptional  Regions.  In  the  dryer  portions  of  the  table- 
land of  Brazil  (see  Map  of  the  Mains'),  the  vegetation  consists  of 
stunted  deciduous  trees  and  extensive  grassy  plains,  interspersed 
with  myrtles  and  other  shrubs.  The  agave  and  the  cactus,  — the 
latter  peculiar  to  the  New  World,  —  also  abound  in  these  hot,  arid 
plains. 

The  Llanos,  of  the  Orinoco  basin,  are  covered  with  tall  grasses, 
intermingled  with 
lilies  and  other 
bulbous  flowering 
plants  in  great  vari- 
ety and  beauty, 
with  here  and  there 
groves  of  palms  and 
mimosas. 

The  Pampas, 
within  and  south 
of  the  La  Plata  ba- 
sin, are  covered 
with  tall  grass,  clo- 
ver, and  thickets  of 
gigantic  thistles  ; 
while  the  barren 
plains  of  Patagonia 
yield  only  coarse 
grass,  growing  in 
tufts,  and  the 
stunted,  thorny 
bushes  characteris- 
tic of  desert  lands. 

West  of  the  An- 
des, throughout  the 
zone  of  the  trade  winds,  the  scarcity  of  moisture  is  such  as  to  render 
the  soil,  in  general,  barren,  except  where  irrigation  is  resorted  to. 
Chili,  in  the  region  of  the  return  trades,  is  well  supplied  with  moist- 
ure, and  has  a  rich  flora.  Extensive  forests  clothe  the  mountain 
slopes,  including  majestic  trees  of  many  kinds,  which  support  a  beau- 
tiful growth  of  climbing  and  parasitical  plants. 

The  araucaria  iinbricata,  a  species  of  fir  tree  with  large  cones  inclosing  edible 
seeds,  growa  in  the  Andes  of  Chili  and  Patagonia,  and  yields  a  large  amount  of 
nutriment  invaluable  to  the  native  inhabitants.  The  potato,  now  cultivated  so 
extensively  in  Europe  and  North  America,  is  indigenous  to  southern  Chili ;  also 
the  fuchsias,  the  much  admired  ornaments  of  our  green-houses  and  gardens. 


III.  Australia. 

1.  General  Character.  The  flora  of  Australia,  though  in- 
cluding some  species  kindred  to  those  of  southern  Africa  and  South 
America,  is  yet,  in  general,  of  a  very  exceptional  character.  Many 
entire  orders  of  plants  are  known  only  in  Australia;  and  the  repre- 


Eucalyptus, 


CHARACTERISTIC   VEGETATION  OF  AUSTRALIA. 


sentatives  of  those  families  which  are  found  elsewhere,  here  appear 
in  new  and  peculiar  forms.  Scarce  an  edible  fruit,  grain,  or  vege- 
table of  any  sort,  is  indigenous  in  this  remarkable  continent. 

The  scantiness  of  foliage,  and  the  sombre  hues  and  stiff,  lustreless 
leaves  of  the  almost  shadeless  forests,  unvarying  in  tint  from  season 
to  season,  —  and  composed  of  scattering  trees,  with  little  or  no  un- 
dergrowth, —  give  an  aspect  to  the  Australian  landscape  unlike  that 
of  any  other  quarter  of  the  globe. 

2.  Forests.  The  myrtle  tribe,  including  the  eucalyptus  (see 
illustration)  and  other  trees  with  beautiful  flowers  of  white,  purple, 
yellow,  and  crimson,  are  the  most  numerous  of  Australian  trees. 
They  grow  with  rapidity,  and  frequently  attain  great  size,  some  of 
the  eucalypti  being  over  400  feet  in  height,  the  tallest  of  known 
trees.  Their  leaves  are  usually  elongated  and  dispersed,  and  hang 
down  vertically,  thus  presenting  only  the  edge  to  the  light,  and 
casting  but  little  shadow. 

Next  in  point  of  numbers  are  the  acacias,  of  which  there  are  nearly 

10  0  species.  The 
footstalks,  placed 
with  their  edges  to- 
wards the  stem,  re- 
place leaves  in  the 
larger  number  of 
these  singular 
plants.  They, 
chiefly,  form  those 
impenetrable  thick- 
ets, called  scrub, 
which  cover  vast 
tracts  of  the  dry 
interior. 

The  easuariimx, 
or  marsh-oaks,  pro- 
d  u  c  i  n  g  excellent 
timber,  have  long, 
slender,  wiry 
branches,  with 
scale-like  sheaths 
instead  of  leaves ; 
and  combine  with 
the  eucalyptus  and 
acacia  to  give  that 
singular  aspect  to  the  Australian  landscape,  remai'ked  by  travellers. 

3.  Local  Flora.  The  epacris  (a  flowering  shrub  similar  to 
the  heaths),  with  scarlet,  rose-colored,  and  white  blossoms  ;  proteas 
in  great  variety  and  beauty  ;  a  gigantic  lily,  with  brilliant  crimson 
flowers  ;  and  the  zamia,  having  the  appearance  of  a  dwarf  palm  — 
are  all  abundant  in  southeastern  Australia. 

In  the  southwest  the  grass  tree,  with  a  tall  trunk  crowned  with 
tufts  of  long,  grassy  leaves,  grows  on  the  sandy  plains  ;  and  plants 
with  dry,  everlasting  blossoms  are  numerous.  Reeds  of  great  size 
often  cover  the  moist  lands  along  the  streams  ;  and  open  grassy 
plains  are  frequent  in  all  the  Southern  part  of  the  continent. 

In  the  northeast  some  peculiar  varieties  of  the  fig  family  grow, 
the  pandanus  flourishes  in  the  neighborhood  of  the  sea,  and  a  few 
species  of  palm  are  found  along  the  eastern  coasts.  On  the  northern 
coasts  are  many  species  of  plants  belonging  to  the  flora  of  the  In- 
dian Archipelago,  among  others  the  cabbage  palm,  some  species  of 
nutmeg,  and  tin;  sandal-wood. 


0°  Singapore                     5° 

10" 

Madras 

15° 

20" 

Calcutta           25" 

30  "Cairo 

t?hounp.  Ihtratwn  of  the  longest  tiay'  in  different  latitudes 

M  JlOUrS 

/J  A  30  m. 

14-hour.Y 

FaJirenlieii  <S#*  Meatt  Temperature  at  the  Level  ofthe  Sea 

*?« 

#0° 

7S° 

74° 

7f° 

VI.  — ASPECTS  OF  NATURE  IN  DIFFERENT  ZONES. 

Explanation  of  the  Diagram.  The  above  diagram  is  designed  to  repre- 
sent the  different  climates  of  the  globe,  from  the  Equator  to  the  northern  limits  of 
the  continents,  about  latitude  72°;  and  to  exhibit,  in  the  varying  angle  at  which  the 
Sun's  rays  strike  the  surface  of  the  Earth  (see  page  70,  Topic  L,  2),  the  grand  cause 
of  the  diversity,  in  light,  in  temperature,  and  in  the  development  of  life,  both 
vegetable  and  animal. 

The  oblique  lines  which  traverse  the  diagram,  represent  the  increasing  obliq- 
uity of  the  sun's  rays;  from  equatorial  to  polar  latitudes ;  and  the  colors  of  the 
background,  varying  from  fiery  red  at  the  left  to  cold  blue  at  the  right,  show  the 
diminution  in  the  intensity  of  heat  and  light  consequent  upon  the  greater  obliquity. 
The  duration  of  the  longest  day,  and  the  mean  annual  temperature,  at  the  differ- 
ent latitudes,  are  also  given. 

Some  of  the  principal  animals  and  plants  of  all  the  climates  are  given  in  their 
proper  positions,  thus  showing  the  effect  of  light  and  heat  upon  their  distribution. 
Beneath,  in  their  correct  latitudes,  are  some  of  the  principal  cities  of  each  climate. 


I.  The  Tropical  Regions. 

1.  Law  of  Development  of  Life.  Throughout  the  entire 
realm  of  nature,  in  the  animal  world  as  well  as  in  the  vegetable,  the 
development  of  life  increases  in  energy,  and  in  the  variety  and  per- 
fection  of  the  types,  with  the  increasing  intensity  of  light  and  heat, 
from  the  poles  to  the  equator. 

2.  The  Vegetable  Woeld.  Within  the  tropics,  under  the 
stimulating  rays  of  a  vertical  sun,  grow  the  most  dense  and  varied 
forests,  the  most  expanded  foliage,  and  the  largest  and  the  most 
brilliant  flowers.  Here,  also,  are  found  the  most  delicious  fruits,  the 
most  powerful  aromatics,  the  greatest  variety  of  plants  capable  of 
affording  sustenance  to  man,  and  the  largest  number  of  those 
which  contribute  to  the  luxuries  of  civilized  life. 


ASPECTS    OF    NATURE    ! 

3.  The  Animal  World.  In  the  tropical  regions,  also,  are  found 
the  greatest  variety  of  species  of  land  animals ;  with  the  highest 
types,  the  greatest  stature,  the  most  intense  activity,  and  the  keen- 
est intelligence  exhibited  in  the  brute  creation. 

This  zone  is  the  home  of  the  gigantic  elephant  and  giraffe  ;  of  the 
lion  and  the  tiger,  the  most  powerful  of  all  the  beasts  of  prey  ;  and 
of  the  gorilla,  chimpanzee,  and  orang-outang,  of  all  animals  most 
like  to  man  in  figure  and  organization. 

Here,  also,  are  the  ostrich,  the  largest  and  most  powerful  of 
birds  ;  the  condor,  surpassing  in  size  all  other  birds  of  flight ,  and 
the  humming-birds  of  South  America,  the  smallest  of  the  feathered 
tribes,  unsurpassed  in  brilliancy  of  coloring,  rapidity  of  motion,  and 
grace  of  form. 

In  the  same  zone  are  those  enormous  reptiles,  the  crocodile  and  the 
boa-constrictor,  with  the  hooded  snakes  and  other  serpents  of  most 
deadly  venom  ;  and  insects  of  all  sizes  in  indescribable  profusion. 


II.  Temperate  Regions. 

1.  In  the  Warm-temperate  Zone,  though  the  sun  never  reaches 
the  zenith,  yet  during  the  long  summer  his  rays  are  almost  vertical ; 
while  the  winter  is  so  mild  that  snow  and  ice  are  of  rare  occurrence. 

Here  the  vegetable  world  is  less  prodigal  in  species,  and  less  luxu- 
riant in  growth,  than  in  the  tropical  regions  ;  still,  verdure  is  con- 
tinuous throughout  the  year,  and  fruits  and  flowers  succeed  each 
other  almost  without  interruption. 

The  animal  world  shows  a  similar,  though  less  marked,  decrease 
in  the  exuberance  of  life.     The  higher  orders  are  less  numerous, 


s*»-^ft**s. 


45* 

Paris  50  ■ 

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55  "Edinburgh 

60  SIPelprsbuT] 

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7 6  hours 

IShJOm 

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MA. 

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24  Jiours 

SJ" 

■78' 

40* 

3J* 

>EF.  CERENT    LATITUDES. 

t  le  individuals  less  gigantic  and  powerful ;  yet  the  antelopes,  among 
most  graceful  of  animals,  and  the  camel,  one  of  the  most  useful, 
e  -pecially  characterize  this  zone. 

2.  In  the  Temperate  Zone,  farther  from  the  tropics,  and   re- 
ring  the  Sun's  rays  with  greater  obliquity,  all  the  forms  of  wge- 
''  ible  growth  are  more  modest  than  in  the  preceding.    The  forests  are 
1'  ;ss  dense  and  varied,  the  foliage  is  less  luxuriant,  and  flowers  of 
b  rilliant  hues  are  confined  to  shrubs  and  herbaceous  plants. 

Though  useful  plants  are  numerous,  yet  scarce  a  species  is  of  value 
11 1  its  spontaneous  growth  ;  and,  above  all,  the  long  dormant  season, 
v  hen  the  trees  and  shrubs  are  bare  and  apparently  lifeless,  stamps 
tl  le,  vegetation  of  this  zone  with  an  aspect  of  inferiority. 

■  The  ^animal  world  still  shows  a  large  number  of  noble  species ; 
there  are  some  orders  which,  like  the  plants,  are  dormant  during 
winter  ;  while  many  of  the  birds  migrate  to  warmer  climes. 

Here  —  associated  with  deciduous  forests,  boundless  fertile  prai- 
ries,  and  arid  steppes — are  the  bear,  the  wolf,  the  lynx,  the  bison, 
a  nd  many  species  of  elk  and  deer.  Here  is  the  home  of  the  horse, 
Hie  ass,  and  many  varieties  of  oxen,  sheep,  and  goats,  —  those  an- 
uJnals  which,  domesticated  by  man,  have   accompanied  him  to  all 

nes,  adapting  themselves  to  all  circumstances. 

j  The  American  turkey,  the  European  pheasant,  and  the  Asiatic 
parents  of  many  of  our  domestic  fowls,  also  belong  to  the  temperate 
z,)ne;  toother  with  a  multitude  of  song  birds,  whose  sober  plu- 
g  so  gloomily  with  the  brilliant  colors  of  their  neigh- 
's compensated  by  the  sweetness  of  their  notes, 
f  the  honey-bee,  and  of  the  silk-worm, 
tectly  useful  to  man. 


n.r  r 

b 


IV.  061(1  Regious. 

1.  General  Aspect.  In  these  regions,  where  the  sun  is  always 
low,  and  in  winter  is  above  the  horizon  but  a  small  part  of  the 
time,  all  nature  becomes  increasingly  monotonous.  The  com.  ts, 
with  their  stiff  forms  and  sombre  hues,  impart  a  dreary  aspect  i 
to  the  summer  landscape  ;  and,  during  the  long  winter,  all  life  seems 
suspended. 

2. .  The  animal  WORLD,  however,  is  more  rich  and  varied  thai) 
the  vegetable. 

In  the  zone  of  the  conifers  we  meet  the  great  moose  and  the 
brown  bear,  the  beaver  and  other  rodents,  in  large  numbers  ;  the 
sable,  the  mink,  the  ermine,  and  a  host  of  other  animals  whose 
fine,  soft  furs  form  one  of  the  main  resources  of  this  inhospitable- 
clime. 

In  the  Arctic  Zone  —  where  these  forests  give  place  to  dwarf  trees, 
stunted  or  creeping  shrubs,  mosses,  and  lichens  —  the  reindeer,  tho 
musk-ox,  and  the  white  bear  are  the  only  representatives  of  the 
larger  land  animals,  though  the  smaller  furry  tribes  are  still  nu- 
merous. 

The  sea,  however,  more  genial  in  its  temperature  than  the  laud, 
swarms  with  living  creatures  of  innumerable  species,  among  which 
are  the  largest  representatives  of  the  animal  kingdom. 

The  whale,  the  walrus,  and  the  seal,  inhabit  the  Arctic  seas ; 
with  every  gr*-  le  of  marine  life,  down  to  the  animalcube,  which 
are  so  numerous  as  to  give  their  color  to  great  areas  of  sea  watefr 
and  water-fowl,  without  number  and  of  many  varieties,  enliven  the 
icy  shores. 


r 


- 


108 


ANIMAL   LIFE  IN  THE  NORTHERN  CONTINENTS. 


—ANIMAL  LIFE  IN  THE  NORTHERN  CONTINENTS. 


iieral  Similarity. 

• .  Extent  of  Resemblance.      The  three  northern  continents 

like  in  their  general  climatic  conditions,  and  in  their  vegetation 

i  ',  in  the  main,  inhabited  by  the  same  orders  and  genera  of  ani- 

i,  though,  as  in  the  vegetation,  few  species  are  identical.     In- 

.  reptiles,  birds,  and  mammals,  all  appear  in  kindred  species, 

e,  in  mam'  cases,  that  the  superficial  observer  would  declare 

to  be  idenical. 

•  i  8g      oiiMOX.     Antelopes,  of  different  kinds,  are  found  in 
i  he  three  continents  ■  and  the  reindeers,  the  elks,  and  some 
•  kinds  of  deer,  are  so  similar  that  even  zoologists  are  in  doubt 
er  they  are  really  of  distinct  species. 

■  bison  and  musk-ox  of  America,  also,  are  closely  related  to  the 
ta  of  Europe 
he    yak    and 
>xen  of  Asia ; 
e  big-horn 
of  the  Rocky 
.aius  finds  its 
ndred   in    the 
moufflon  of  south- 
ern  Europe,   and 
the  argali  and  other 
ep  of   western 
am!    central  As:.;. 
Goats  of    several 
eies,  and    the 
\vi!  I    boar,   though 
g    in  Ainer- 
are  common  to 
i]  c  and  Asia. 
The  cat  tribe 
aids  in  all  three 
inents  ;     also 
rs,  wolves,  dogs, 


foxes.    The  ro- 
of   gnawers 
vers,  r a  b  b i  ts ,  characteristic  am.m 

rels,  rats,  mice,  etc.) ;  and  the  minks  and  ermines,  with  others 
of  their  tribe,  are  but  slightly  different  in  the  several  continents. 

II.  ^ortli  America. 

4 

1.  Characteristic  Animals.  North  America,  with  its  wealth 
loisture  and  abundance  of  vegetation,  and  its  vast  rivers  and 
:,  is  characterized  by  the  predominance  of  the  herbivorous  over 
carnivorous  animals ;  by  the  great  number  of  rodents,  many  of 
h  are  aquatic  animals  ;  and  by  its  innumerable  water-fowls, 
jarly  all  the  orders  of  the  Old  World,  including  both  web-footed 
i  and  waders,  are  represented  in  North  America,  with  many 
.liar  to  the  New.     Other  birds  are  very  numerous,  among  which 

ntinent;  various  kinds  of  pigi 
defy  of  oth 

move 

i 


2.  Other  Species.  The  brown  and  the  white  bear  inhabit  the 
Arctic  regions  ;  the  grizzly  bear,  the  largest  and  most  ferocious  of 
its  kind,  is  found  in  the  Rocky  and  Sierra  Nevada  Mountains ;  and 
the  black  bear,  in  the  forests  of  the  east.  Dogs  are  indigenous  in 
the  far  north,  where  some  varieties  have  been  domesticated. 

The  puma,  or  American  lion  — commonly  called  the  panther  —  is 
the  most  powerful  animal  of  the  cat  tribe  belonging  to  North  Amer- 
ica, and  replaces  in  this  continent  the  lion  and  tiger  of  Asia. 

III.-  Asia-Europe. 

1.  Asia  is  especially  characterized  by  the  great  number  of 
animals  capable. ^of  domestication*  which  are  found  in  every  part  of 
the  continent.  The  horse,  the  ass,  and  the  yak ;  the  valuable  Cash- 
mef&  and  Angora  goats  ;  several  varieties  of  sheep  ;  and  the  Bactrian 
camel,  with  t\vt>  fatH»£S,  are  all  indigenous^    ^^,r.  ,  :  •..  0"d  aU 

were   already  the 
servants  of  man 
the  dawn  of  his- 
tory. 

Southern  Asia 
has  the  swine,  and 
the  gigantic  ele- 
phant; the  zebu 
and  the  buffalo, 
early  domesticated 
by  the  native  man, 
together  with  a 
number  of  other 
(ix  en  still  wild. 
Western  Asia  lias 
the  dromedary,  or 
Arabia  n  camel, 
VI  ith  one  hump  ; 
the  Syrian  ox.  and 
several  sheep  am! 
goats ;  and  north- 
ern Asia,  has  the 
reindeer. 

2.  Tbopical 
Asia,  which  in- 
cludes the  Indian  Archipelago  and  the  adjacent  peninsulas,  is  the 
home  of  the  highest  orders  of  animals,  though  their  species  are  less 
numerous  than  in  Africa. 

Here  are  found  the  orang-outang,  so  like  to  the  human  form  that 
he  is  called  by  the  Malays  the  man  of  the  woods ;  many  species  of 
apes  and  monkeys  peculiar  to  Asia ;  and  the  Indian  elephant,  the 
.rhinoceros,  the  tapir,  and  the  wild  boar. 

The  carnivorous  animals  are  numerous  and  powerful.  The  royal 
tiger,  the  handsomest  and  moflQ  formidable  of  these,  inhabits  the 
jungles  of  Hindoostan ;  leopards  and  panthers  are  common,  and  the 
lion  is  seen  in  some  parts  of  Indo-China. 

Four  species  of  bears  are  found  in  India,  and  wolves,  foxes,  hye- 
nas, and  jackals  occur  nearly  everywhere. 

the  largest  known  speck-  Iv  of  which 

TO,  with  man 

E 

I 


\LS  OF   NORTHERN   CONTINENTS. 


White  Bear. 
"Wild  Turkey.     Beaver. 


ANIMALS    OF   THE   SOUTHERN   CONTINENTS. 


109 


hues.  This  is  the  home  of  the  great  green  parrot,  so  easily  taught 
to  speak,  with  a  host  of  kindred  species  of  eyery  color  ;  of  the  pea- 
cock, and  of  the  beautiful  gold  and  silver  pheasants.  From  here, 
also,  our  common  domestic  fowls  are  derived. 

The  crocodile  and  other  reptiles  frequent  the  rivers,  venomous 
snakes  being  especially  numerous  ;  and  insects  of  large  size  and  bril- 
liant tints  abound. 

3.  Europe,  which  forms  the  peninsular  headland  of  the  great 
double  continent,  has  no  family  or  order  of  animals  peculiarly  its 
own  ;  and  a  large  number  of  its  species  are  found  in  Asia  or  North 
America.  Western  Asia,  Europe,  and  the  Mediterranean  region  of 
Africa,  so  closely  united,  form  but  one  zoological  province,  the  prin- 
cipal types  of  animals,  as  of  plants,  being  nearly  identical. 

The  European  reindeer,  goat,  fallow-deer,  red  deer,  swine  and  cat, 
have  all  been  domesticated ;  and  it  is  possible  that  the  moufflon 
of  Corsica,  and  the  wild  cattle  of  Britain,  may  be  the  parents  of 
the  indispensable  domestic  sheep  and  kine. 

VIII.  —  ANIMALS  OF   THE  SOUTHERN    CONTINENTS. 

I.  Africa. 

1.  General  Character.  The  mammalia,  the  highest  division 
of  the  animal  kingdom,  are  especially  characteristic  of  Africa,  the 
highest  orders  occurring  in  greater  numbers,  both  of  species  and  of 
individuals,  than  in 
any  other  conti- 
nent. More  than 
two-thirds  of  the 
species  inhabiting 
this  continent  are 
peculiar  to  it, 
though  many  are 
represented  by  kin- 
dred species  in  trop- 
ical Asia. 

Since  so  large  a 
part  of  Africa  is 
either  utterly  bar- 
ren, or  covered  by 
temporary  vegeta- 
tion and  watered 
liy  stream  s  that 
flow  only  during  the 
rainy  season,  fleet 
animals,  fitted  to 
live  on  arid  plains, 
and  the  carnivorous 
animals,  which  prey  characteristic 

upon  them,  are  particularly  numerous.     The  most  biaky  species  </f 
the  land  animals  also  abound  in  equatorial  Africa,  especially  in  the 
regions  and  in  the  neighborhood  of  the  coasts. 

■1.  The  ABED  REGIONS  of  southern  Africa  and  the  borders  of  the 
Sahara,  which  during  the  rainy  season  have  a  rich  and  varied  vege- 
tal ion,  are  inhabited  by  immense  herds  of  antelopes,  of  almost 
innumerable  species,  among  which  the  eland  is  the  largest,  and  the 
gnu  the  most  peculiar  ;  by  the  zebra,  and  its  kindred  the  quagga  — 
animals  of  the  horse  kind;  together  with  lions,  leopards,  panthers, 
and  other  beasts  of  prey,  everywhere  numerous.  The  ostrich  also 
abounds  in  the  arid  plains  both  of  Northern  and  of  Southern  Africa. 


leopard. 
Gnu.  Lion. 


3.  Equatorial  Africa.  Principal  Mammals.  This  portion 
of  Africa  is  the  home  of  species  of  the  elephant  and  rhinoceros  dif- 
fering from  those  in  Asia ;  of  the  hippopotamus,  peculiar  to  Africa ; 
and  of  the  wild  boar. 

The  giraffe,  or  cathelopard,  the  largest  of  the  ruminants,  also  pe- 
culiar to  Africa,  is  found  everywhere  south  of  the  Sahara  ;  together 
with  several  varieties  of  oxen  and  buffaloes,  sheep  and  goats. 

The  chimpanzee  and  the  gorilla,  kindred  to  the  orang-outang,  in- 
habit the  forests  of  the  western  coasts  ;  with  apes  and  monkeys 
of  many  species,  and  large  bats  in  great  numbers. 

Birds  in  great  variety  abound,  there  being  no  less  than  59  species 
of  birds  of  prey  in  this  continent.  Kingfishers  and  swallows,  the 
most  brilliantly  colored  of  their  kinds  ;  and  guinea-fowls  in  im- 
mense flocks,  frequent  the  margins  of  the  lakes  and  streams. 

Web-footed  birds  and  waders  are  also  numerous.  Among  these 
are  the  beautiful  Numidian  crane,  the  ibis,  the  sacred  bird  of 
the  ancient  Egyptians,  and  the  flamingo. 

Honey-birds,  the  representatives  of  the  American  humming-birds, 
abound  in  South  Africa,  where  the  many  flowering  plants  supply 
them  with  food. 

The  crocodile  and  other  reptiles  inhabit  the  marshes  and  the  bor- 
ders of  the  lakes  and  streams  ;  and  tree  serpents,  also,  are  numerous. 
Among  the  latter  is  the  python,  the  Old  World  kindred  of  the 
American  boa-constrictor. 

II.  South  America. 

1.  General 
Character. 
South  America, 
with  its  wealth  of 
moisture  and  its 
luxuriant  vegeta- 
t  i  o  n ,  is  distin- 
guished  by  animals 
quite  unlike  the 
predominant  spe- 
.  cies  of  Africa. 
"Those  which  give 
the  peculiar  char- 
acter of  the  an- 
imal world  in 
South  America,  are 
such  as,  by  their 
mode  of  life,  are 
connected  most 
closely  with  the 
vegetable  kingdom 
and  the  waterv 
animals  of  Africa.  element. 

The  insect  world  is  nowhere  more  rich,  varied,  and  beautiful.  The 
variety  of  species  is  almost  inexhaustible,  while  in  brilliancy  of  col- 
oring and  size  of  the  body  they  are  unsurpassed. 

The  reptiles,  for  which  the  many  rivers,  and  the  lagoons  of  the 
rainy  season,  furnish  a  most  suitable  abode,  are  especially  nume- 
rous. 

The  alligator  — -  the  crocodile  of  the  New  World— multiplies  in 
the  warm,  sluggish  waters  ;  and  those  gigantic  lizards,  the  iguana 
and  the  basilisk,  abound.  The  forests  harbor  serpents  in  immense 
numbers,  and  of  almost  every  variety,  including  the  monstrous  boa- 
eonstrictor,  the  terror  even  of  the  native  inhabitants. 


Rhinoceros. 

Flamingo. 


Elephant.  Giraffe. 

Ibii.     Hippopotamus. 


Chimpanzee.    Ostrich. 
Crocodile.     Hyena. 


110 


ANIMALS   OF  THE   SOUTHERN   CONTINENTS. 


2.  Characteristic  Birds.  The  most  characteristic  birds  are 
the  stilt-plovers,  inhabitants  of  the  marshes  and  the  shores,  the  spe- 
cies of  which  are  more  numerous  in  South  America  than  in  any 
other  continent.  Other  waders  and  water-fowls  without  number 
are  found  here,  including  flamingoes,  herons,  ducks,  and  gulls.  Of 
the  humming-bird,  which,  is  confined  to  the  New  World,  there  are 
150  species  in  South  America,  the  continent  of  flowering  forests,  and 
but  four  in  the  whole  of  North  America. 

Among  other  birds  peculiar  to  South  America,  are  the  toucan, 
with  vivid  colors  and  an  enormous  beak  ;  and  a  number  of  species 
of  long-tailed  parrots,  inferior  in  intelligence  to  those  of  India. 

The  condor,  the  largest  of  vultures,  inhabits  the  Andes  at  15,000 
feet  or  more  above  the  sea.  The  rhea,  or  American  ostrich,  lives  on 
the  treeless  plains  of  the  La  Plata  basin,  and  a  bird  of  kindred 
species  roams  the  high,  arid  plains  of  Patagonia. 

3.  Characteristic  Mammals.  Among  the  mammals,  also, 
the  dominant  types 
are  those,  of  an  in- 
f  e  r  i  o  r  character. 
Opossums,  a  subdi- 
vision of  the  marsu- 
pials,1 the  lowest  of 
the  mammals  in  or- 
ganization, are  nu- 
merous, but  none 
are  much  larger 
than  a  rat. 

The  order  of 
edentata  —  includ- 
ing the  armadillo, 
pangolin,  ant-eater, 
and  sloth  —  is  es- 
pecially character- 
istic of  South 
America.  This 
continent  has 
twenty  species  of 
these  animals,  while 
but  four  species  oc- 
cur in  Africa  and 
Asia  together. 

4.  Higher  Orders 


Boa  Constrictor. 
Armadillo. 


Condor. 
Ant-Eater.  Crocodile. 


CHARACTE1IISTIC  ANIMALS  OF   SOUTH  AMERICA 

The  South  American  representatives  of 
the  higher  orders  are  smaller,  less  strong,  and  in  every  respect  infe- 
rior to  the  corresponding  animals  of  the  Old  World.  Instead  of 
the  gigantic  elephant,  rhinoceros,  and  hippopotamus,  and  the  fierce 
wild  boar,  South  America  has  in  this  order  only  the  feeble  and 
harmless  tapir,  and  the  peccary. 

In  place  of  the  camel  and  dromedary,  antelopes,  oxen,  sheep,  and 
other  ruminating  animals,  —  so  numerous  in  Africa  and  tropical 
Asia,  —  South  America  has,  besides  a  few  deer,  only  the  llama,  al- 
paca, and  vicuna  of  the  Andes,  and  the  guanaco  of  the  plains.  The 
llama,  though  allied  to  the  camel,  is  scarce  half  its  size,  and  has  not 
a  tithe  of  its  strength  or  endurance. 

The  majestic  lion,  tiger,  and  leopard,  are  represented  in  South 
America  by  the  puma,  the  ounce  or  jaguar,  and  the  ocelot,  which, 
though  fierce  and  powerful,  are  much  smaller  than  their  Old  World 
kindred. 


1  Animals  provided  with  a  pouch  for  carrying  their  young,  which  are  produced  in  a  much 
less  developed  condition  than  the  young  of  other  mammals. 


The  monkeys  of  South  America,  also,  —  with  a  prehensile  tail, 
and  a  wide,  flat  nose,  —  are  of  a  lower  order  than  the  taillesB  mon- 
key of  the  Old  World  ;  while  the  apes,  more  resembling  the  human 
form,  are  entirely  wanting  in  this  continent. 


III.  Australia. 

1.  General  Character.  The  fauna  of  Australia  differs  from 
that  of  all  other  continents  as  greatly  as  does  its  flora.  Its  animals 
are  not  only  feAV  in  species,  and  in  numbers  when  compared  with 
the  extent  of  the  continent,  but  are  of  a  very  unusual  type.  The 
majority  are  peculiar  to  this  continent,  and  have  not  even  kindred 
types  elsewhere. 

2.  Characteristic  Animals.  Australia  is  especially  charac- 
terized by  the  marsupials,  which  inhabit  this  continent  in  great 
numbers,  and  all  of  which,  with  the  exception  of  the   opossums,  are 

confined  to  Austra- 
lia and  its  islands. 
The    Australian 
marsupials   include 
a  large  number  of 
families,  some   of 
which  are  carnivo- 
rous, others  herbiv- 
orous.     Many   re- 
semble  in   their 
habits,  and  to  a 
certain  extent  in 
appearance,     a  n  i  - 
mals  of  higher  or- 
ders in  other  conti- 
nents.     The  most 
numerous  and  char- 
acteristic,   as   well 
as  the  largest,  are 
the    kangaroos,   of 
which    there    are 
nearly  forty  species. 
The  ornitho- 
rhynchus  and  the 
echidna     (illustra- 
tion, p.  Ill)  are  the  most  remarkable  of  Australian  animals.     The 
former,  which  is  covered  with  fur,  has  a  head,  body,  and  legs  similar 
to  a  quadruped,  with  the  bill  of  a  duck,  and  partially  webbed  feet. 
The  latter,  similar  in  organization,  is  covered  with  quills  like  a  por- 
cupine, is  a  burrowing  animal,  feeds  on  ants,  and  lies  dormant  during 
the  winter. 

3.  Higher  Orders.  The  large,  noble,  and  powerful  animals, 
so  numerous  in  Africa,  are  entirely  wanting  in  Australia,  as  are  also 
the  monkeys,  so  abundant  in  both  of  the  other  southern  continents. 
There  are  no  native  ruminating  animals,  large  or  small ;  nor  any 
beasts  of  prey  larger  than  the  wild  dog,  or  dingo,  and  a  carnivorous 
marsupial  called  the  Tasmanian  wolf. 

4.  The  BIRDS  of  Australia  are  no  less  peculiar  than  the  mam- 
mals. Among  them  are  the  beautiful  lyre  bird,  and  the  birds  of 
paradise ;  a  large  number  of  parrots  and  cockatoos,  unlike  those  of 
the  other  continents;  the  emu  and  the  cassowary,  birds  of  the  ostrich 
kind,  which  inhabit  the  arid  plains  of  the  interior ;  and  apteryx, 
whose  singular  forms  recall  the  birds  of  geological  times. 


Jaguar. 


lguuuu. 


PROVISION  FOR  HUMAN   LIFE   AND   CIVILIZATION. 


Ill 


n.— PROVISION    FOR    HUMAN    LIFE. 
I.  _FOOD,  RAIMENT,  AND  SHELTER. 

I.  Introduction. 

Man,  even  in  the  most  primitive  conditions  of  society,  must  pro- 
vide himself  with  food,  raiment,  shelter  from  the  elements,  and  im- 
plements with  which  to  accomplish  his  designs.  Nature  furnishes 
him  the  materials  for  all  these,  which  he  employs,  either  in  their 
crude  state,  or  in  modified  forms  which  are  the  result  of  his  own 
activity  and  skill.  Of  all  the  vast  wealth  of  nature,  however, 
whether  in  the  vegetable,  the  animal,  or  the  mineral  kingdom,  com- 
paratively few  things  are  directly  useful  in  supplying  the  wants,  or 
contributing  to  the  progress,  of  the  human  family. 


Food  sufficient  for  the  support  of  life, 


II.  Sustenance. 

1.  Extent  of  Supply. 
either  from  the  veg- 
etable or  the  animal 
kingdom,  is  found 
in  all  climes,  for  all 
are  inhabited.  The 
materials  employed, 
however,  vary  with 
the  climate. 

2.  In  the  Trop- 
ical Zone  the  diet 
of  the  native  man  is 
almost  exclusively 
vegetable ;  and  is 
obtained  from 
plants'growing 
spontaneously,  and 
furnishing  a  con- 
stant supply  of  food 
in  all  seasons  of  the 
year. 

Chief  among  these 
are  the  bread-fruit 
tree  (Artocarpus), 
and  kindred  spe- 
cies ;  the  banana 
(Musa),  the  manioc  (Jatropha  manihot),  the  arum  or  taro  (Colo- 
casia),  the  yams  (Dioscorea),  and  the  palms. 

3.  In  the  Tempeeate  Zone,  a  considerable  proportion  of  the 
food  consists  of  animal  substances,  and  the  food-plants  require  cul- 
tivation to  make  them  available  to  any  extent. 

The  native  fruits,  grains,  and  edible  roots,  or  root-stocks,  are,  in 
their  wild  condition,  of  little  value  for  purposes  of  nutrition,  and  are 
confined  to  limited  areas;  while  the  long  dormant  season  of  winter 
cuts  off  all  supplies  for  a  part  of  the  year.  Hence  in  this  zone, 
where  nature  furnishes,  so  to  speak,  only  the  germs  of  food-plants, 
man  is  obliged  constantly  to  supplement  her  work  by  forethought 
;md  intelligent  labor. 

The  animal  food,  hi  the  Old.  World,  has  been  from  time  immemo- 
rial derived  chiefly  from  domesticated  animals ;  while  the  native 
man  of  the  New  World  seems  to  have  always  depended  on  the  wild 
animals  of  the  chase,  few  tribes  having  risen  above  the  condition  of 
hunters. 


Cockatoo.    Bird  of  Paradise. 
Bandicoot.   Apteryx. 


Kangaroo. 


Lyre  Bird.  Kangaroo  Rat 

CHARACTERISTIC   AUIMAL8   OF  AUSTRALIA 


4.  In  the  Frigid  Zone,  food-plants  are  almost  entirely  wanting, 
The  sustenance  of  the  native  man  is  chiefly,  if  not  whcdy,  animal ; 
and  is  derived  to  a  great  extent  from  the  inhabitants  of  the  sea. 

4.  Food  Plants  of  Civilized  Nations.  The  main  sources 
of  the  vegetable  fo'df,  of  civilized  nations  are  the  cereals,  —  including 
wheat,  rye,  oats,  bafclev,  maize,  millet  or  durrah, and  rice  ;  the  differ- 
ent varieties  of  pulse,  —  as  peas,  beans,  and  lentils  ;  a  few  plants 
yielding  esculent  tubers,  bulbs,  roots,  or  leaves,  —  as  the  potatd,  swdfet 
potato,  onion,  beet,  carrot,  and  cabbage  ;  the  cucumber  family,  as  the 
melon,  squash,  etc.  ;  and  a  few  succulent  fruits,  chiefly  of  the  apple, 
pear,  peach,  plum,  grape,  and  citron  families. 

Millet  forms  the  chief  bread  corn  of  Africa,  and  is  commonly  used  in  tropical 
Asia  also ;  but  rice  probably  furnishes  sustenance  to  a  larger  proportion  of  the 
human  family  than  any  other  single  plant,  being  in  constant  use,  as  the  chief  article 
of  diet,  in  India,  China,  and  Japan.  The  other  cereals,  with  the  exception  of 
maize,  do  not  thrive  within  the  tropics,  except  on  the  elevated  lands. 

The  date  replaces  bread  to  a  great  extent  among  the  inhabitants  of  the  arid 
regions  of  northern  Africa  and  western  Asia,  where  it  is  cultivated  in  the  oases. 


III.  Luxuries. 

1.  Articles  of 
Luxury.  There  are 
other  articles  which, 
though  not  essential  to 
the  sustenance  of  the 
body  —  some  being 
even  highly  injurious 
—  are,  nevertheless,  in 
constant  use  among 
the  different  peoples  of 
the  earth.  These  may 
be  distinguished  as  lux- 
uries. 

This  class  includes 
sugar,  and  the  spices, 
which  are  used  as  con- 
diments ;  tea,  coffee, 
and  chocolate,  em- 
ployed as  accompani- 
ments to  solid  food ; 
a  variety  of  stimulating 
beverages ;  and  nar- 
cotics, especially  tobac- 
co, opium,  and  hash- 
ish which  is  extracted 
from  the  common  hemp,  and  is  said  to  surpass  opium  in  its  intoxicating  effects. 

Of  the  narcotics,  only  the  first  named  is  used  to  any  extent  in  Europe  and  Amer- 
ica ;  the  second  replaces  it  in  eastern  Asia ;  while  in  western  Asia,  especially  among 
the  Turks,  all  three  are  habitually  employed.  Perfumes  in  great  variety  are  also 
in  constant  use,  both  among  European  and  Oriental  nations. 

2.  Commercial  Importance.  These,  and  other  articles  of  luxury,  the  pro- 
duction of  which  is  confined  to  the  tropical  zone,  or  to  limited  areas  in  temperate 
latitudes,  enter  largely  into  the  commerce  of  the  nations  of  Europe  and  America. 
Thus  they  furnish  occasion  for  that  constant  intercourse  of  the  latter  with  the  less 
advanced  peoples  of  Asia  and  the  barbarous  races  of  the  tropics,  by  which  the 
benefits  of  civilization  are  extending  throughout  the  world.  The  luxuries  of  life 
—  "  spicery,  balm,  and  myrrh  " —  were  also  among  the  earliest  known  articles  of 
commerce.     (See  Metals,  below.)  % 


IV.  Materials  for  Raiment. 

Textile  Materials,  from  either  the  vegetable  or  the  animal 
kingdom, abound  throughout  the  tropical  and  temperate  zones.  Those 
chiefly  in  use  are  ivool,  from  the  sheep  and  goat  of  the  northern  tem- 


Wild  Dog. 

Echidna. 


Oruithorhynchue. 


£mu. 

Banded  Ant-eater. 
Black  Swan. 


112 


MINERALS  EMPLOYED  IN   THE   ARTS. 


perate  zone,  and  the  alpaca  of  the  southern  ;  flax,  the  product  of 
the  northern  temperate  ;  and  silk  and  cotton,  of  the  warm-temperate 
and  the  tropical.  In  the  cold  zones  these  articles  are  replaced  to  a 
great  extent  by  the  furs  and  skins  of  the  wild  animals. 

The  common  hemp  (Cannabis),  a  plant  closely  allied  to  the  nettle,  yields  a  re- 
markably tough  fibre,  capable  of  being  manufactured  into  linen  and  cordage.  The 
leaf  of  the  pine-apple  (A  nana)  furnishes  the  material  from  which  a  delicate  trans- 
parent tissue,  known  as  pina-cloth,  is  woven.  The  leaf  of  the  so-called  New 
Zealand  flax  (Phormium),  a  plant  of  the  lily  family,  affords  a  strong  fibre  similar 
to  flax,  and  was  in  use  among  the  native  inhabitants  of  New  Zealand  at  the  dis- 
covery of  their  island  by  Europeans.  A  considerable  number  of  other  plants, 
especially  within  the  tropics,  furnish  fibres  suitable  for  the  manufacture  of  coarse 
cloth  or  cordage,  and  are.  in  use  among  the  native  peoples. 


V.  Materials  of  Construction. 

Timber  suitable  for  the  construction  of  buildings,  ships,  or  vehicles 
for  land  transportation,  and  the  furniture  and  implements  of  com- 
mon life,  abounds  in  all  of  the  zones ;  but  the  superior  hardness,  rich 
color,  and  fine  grain  of  many  woods  of  the  tropical  zone,  fit  them 
especially  for  the  construction  of  those  articles  in  which  elegance  as 
well  as  durability  is  sought. 

The  rocks  of  the  earth  —  granite,  sandstone,  marble,  etc.  —  every- 
where near  the  surface  except  in  alluvial  plains,  form  an  almost  im- 
perishable building  material ;  and,  where  these  and  timber  are  want- 
ing, clay,  moulded  into  brick,  serves  the  same  purpose.  In  the  frozen 
zone,  among  the  Esquimaux,  even  blocks  of  snow  serve  to  construct 
comfortable  abodes. 


II.    MINERALS   EMPLOYED  IN   THE   ARTS. 

1.  Distribution  in  the  Continents. 

North  America,  in  the  eastern  half,  is  characterized  especially  by 
the  useful  minerals,  coal,  iron,  copper,  and  lead.  The  workable  coal 
fields  of  North  America  exceed  in  extent  those  of  all  other  countries 
taken  together.  The  precious  metals  abound  in  the  West  —  gold 
especially  in  the  Sierra  Nevada  Mountains,  silver  in  the  plateaus  of 
Mexico  and  the  United  States,  and  both  in  the  Rocky  Mountains. 
Mercury,  essential  in  gold  and  silver  mining,  also  abounds  in  Cali- 
fornia. 

Europe  is  characterized  by  an  abundance  and  wide  diffusion  of 
nearly  all  of  the  useful  minerals.  The  precious  metals  occur  in 
many  places,  but,  except  in  the  Ural  Mountains,  and  the  Little 
Carpathians,  they  are  found  only  in  comparatively  limited  quanti- 
ties. Diamonds  are  found  in  the  Urals,  other  gems  are  numerous 
in  Spain  and  Transylvania  ;  and  the  most  beautiful  marbles  abound 
in  the  southern  peninsulas. 

Asia,  like  Europe,  is  distinguished  by  the  variety  of  its  valuable 
minerals.  The  precious  metals  are  found  in  greater  abundance 
than  in  Europe,  especially  in  China,  the  Altai  Mountains,  and  India ; 
also  in  the  Archipelago,  where  they  are  associated  with  diamonds. 
The  diamonds  of  Golconda,  in  India,  were  famous  in  ancient  times, 
but  they  are  now  nearly  exhausted.  Rubies  and  other  gems  are 
found  in  India,  in  Mongolia,  and  elsewhere. 

South  America  possesses  inexhaustible  supplies  of  both  precious 
and  useful  metals,  especially  in  the  Andes,  where  copper  and  silver 
are  particularly  abundant.  Diamonds  abound  in  Brazil,  in  the 
neighborhood  of  its  central  water-shed,  where  gold  is  also  found. 

In  Africa,  so  far  as  known,  iron,  copper,  and  gold  are  the  most 
widely  diffused  of  the  metals,  but  our  knowledge  of  the  mineral 


wealth  of  this  vast  continent  is  very  imperfect.  Rich  diamond  fields 
have  recently  been  discovered  in  the  basin  of  the  Orange  River. 

Australia  is  characterized  by  the  great  abundance  of  gold  in  the 
southeastern  part,  and  the  inexhaustible  supplies  of  the  finest  copper 
in  the  south.  Silver,  mercury,  lead,  zinc,  and  iron  also  are  found  in 
workable  quantities.  Thus  the  poverty  of  the  vegetable  and  the  ani- 
mal world  in  this  continent  is  compensated  by  its  mineral  wealth. 

Iron,  coal,  and  salt,  the  most  indispensable  of  minerals,  are  more 
widely  diffused  than  any  other.  No  continent  is  deprived  of  them, 
and  few  countries  lack  an  abundant  supply. 

Salt,  the  only  substance  used  as  food  which  is  taken  directly  from  the  mineral 
kingdom,  is  obtained  by  evaporation  from  springs,  salt  lakes,  and  sea  water ;  and 
also  occurs  in  beds  of  crystalline  or  rock  salt. 

The  most  famous  of  salt  mines  is  that  at  Wieliczka,  near  Cracow,  in  the  Aus- 
trian Empire.  This  mine,  which  has  been  worked  since  the  middle  of  the  thir- 
teenth century,  and  seems  inexhaustible,  forms  a  veritable  underground  city, 
where  people  pass  their  entire  lives  without  seeing  the  light  of  the  sun.  Our  own 
country  contains  several  rich  salt  beds.  Chief  among  them  is  the  Muddy  Salt 
Mine  in  southern  Nevada,  a  bed  of  pure,  transparent,  crystalline  salt,  with  an 
area  of  two  square  miles  or  more,  and  an  unknown  depth.  Another,  containing 
146  acres,  occurs  in  an  island  of  the  Gulf  of  Mexico,  near  the  mouth  of  Atcha- 
falaya  Bayou. 

The  distribution'  of  coal,  diamonds,  and  the  useful  and  precious  metals,  is 
indicated  on  the  accompanying  map.  Each  has  its  special  sign  and  the  compar- 
ative amount  which  occurs  in  any  given  region  is  indicated  by  the  size  of  the  sign. 

II.  The  Principal  Metals. 

1.  Natural  Conditions.  Iron,  lead,  tin,  mercury,  and  zinc,  in  workable 
quantities,  occur  only  in  the  form  of  ores.  Copper  and  silver  occur  as  ores,  and 
also  in  the  metallic  state.  Native,  or  metallic,  copper  is  found  in  every  continent, 
and  though  much  less  abundant,  is  almost  as  widely  diffused  as  iron. 

Gold  and  platinum  occur  only  in  the  metallic  state,  either  pure,  or  alloyed  with 
silver  or  other  rare  metals.  They  are  found  both  in  mines,  and  also  among 
the  sand  and  gravel  in  river  beds,  or  alluvial  formations  called  placers,  where 
the  debris  of  metalliferous  rocks  have  been  deposited. 

2.  Antiquity  or  Use.  Copper,  which  abounds  as  a  native  metal,  tin,  used 
to  alloy  it,  and  gold  and  silver,  were  in  use  in  western  Asia  in  the  most  remote 
antiquity,  the  first  two  being  the  earliest  employed  in  the  arts  of  life.  Weapons, 
ornaments,  vases,  and  other  works  of  art,  in  pure  copper,  or  in  bronze  formed  by 
alloying  copper  with  ten  per  cent,  of  tin,  are  found  among  the  remains  of  pre- 
historic ages,  where  articles  in  other  metals,  of  equal  antiquity,  are  entirely  want- 
ino\     Lead  and  iron  were,  however,  in  use  in  the  earliest  historic  times. 

Weapons  and  cutting  implements  of  stone,  either  rough  or  polished,  seem  to 
have  preceded  the  use  of  metals  everywhere  except  in  Iran,  Syria,  and  Egypt. 
where  there  are  no  indications  of  a  period  in  which  metals  were  unknown. 


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114 


RACES    OF  MEN. 


Zinc  replaces  tin  in  some  of  the  antique  bronzes,  but  it  seems  to  have  been  pro- 
cured in  the  reduction  of  copper  ores,  with  which  it  often  occurs.  No  zinc  mines 
were  known  until  near  the  Christian  era.  Mercury,  indispensable  to  modern  civ- 
ilization, and  platinum,  invaluable  to  the  chemist,  were  unknown  to  the  ancients. 

3.  Ancient  Mines.  The  following  were  the  chief  sources  whence  the  ancients 
were  supplied  with  the  metals  :  — 

Copper  —  Nubia,  and  the  Sinai  peninsula;  northern  Syria,  Armenia,  and  east- 
ern Asia  Minor  (Pontus)  ;  the  island  of  Cyprus  ;  Greece,  Italy,  and  Spain. 

Tin  —  The  Hindoo  Koosh,  and  the  southern  Caucasus,  —  apparently  little 
worked ;  Spain,  the  peninsula  of  Cornwall  in  England,  and  the  adjacent  Scilly 
Islands.  The  western  mines  alone  supplied  the  merchants  of  ancient  Sidon,  Tyre, 
Phoenicia,  and  Egypt,  with  this  metal,  which  they  transported  even  into  India. 
Tin,  from  its  rarity  and  importance,  was  a  most  precious  metal  of  the  early  ages. 

Silver  and  Gold  —  The  Caucasus,  Armenia,  Pontus,  northern  Syria  and  India  : 
Nubia  and  southeastern  Africa  ;  Spain  and  the  Pyrenees. 

Lead  —  Nubia,  Asia  Minor,  the  Island  of  Sardinia,  Spain,  and  England.  Zinc 
—  Asia  Minor.     Iron  —  Nubia,  Armenia,  the  Caucasus,  Pontus,  Syria,  and  Cyprus. 

4.  Ancient  Commerce.  The  metals,  gems  from  Spain  and  India,  and  amber 
from  the  shores  of  the  Baltic,  with  spices  and  perfumes,  were  the  earliest  known 
objects  of  commerce.  All  the  routes  of  ancient  trade,  and  consequently  of  the 
spread  of  civilization  from  its  earliest  seats  in  western  Asia  and  Egypt,  were 
governed  by  the  distribution  of  these  articles. 


H.  — THE    HUMAN    FAMILY. 


I.  — RACES  OF  MEN. 


I.  Introduction. 


Man,  unlike  the  in- 


1.  Extent  of  Dispeksion  of  Mankind. 
dividual  species  of  animals  or 
of  plants,  is  confined  to  ho  cli- 
mate, to  no  fixed  assemblage  of 
physical  conditions.  Though 
the  greater  portion  of  the  hu- 
man family  inhabit  the  tem- 
perate latitudes,  yet  man  is 
found  in  every  zone  ;  adapting 
himself  alike  to  the  burning 
heat  and  continuous  summer  of 
the  tropics,  and  the  intense  cold 
and  almost  unbroken  winter  of 
the  polar  regions.  All  climes 
furnish  him  materials  for  food, 
raiment,  and  shelter,  suited  to 
his  needs  in  the  circumstances 
which  surround  him. 

2.  Diversity.  Under  the 
influence  of  ever-varying  ex- 
ternal conditions,  the  human 
family,  —  while  preserving  in 
all  climes,  and  under  all  circum- 
stances, certain  common  fea- 
tures of  body  and  mind,  which 
mark  them  as  one,  —  display  an 
almost  unlimited  diversity  of 
physical  and  mental  qualities, 
and  of  social  conditions. 

The  form  and  features  show 
every  gradation,  from  the  sym- 
metry, grace,  and  dignity  of  the  ideal  man,  portrayed  by  the  sculp- 
tors of  ancient  Greece,  to  the  ugliness  and  deformity  of  the  Hot- 
tentot and  the  Fuegian.     The  color  of  the  skin  varies  from  white 


tinted  with  rose,  through  brownish  or  yellowish  hues,  to  an  almost 
jet  black. 

The  temperament  is  here  ardent  and  impulsive,  the  emotions  re- 
sponding with  the  vivacity  of  childhood  to  every  impression,  whether 
joyous  or  sad ;  there  it  is  cold,  passive,  as  in  old  age,  almost  in- 
sensible alike  to  pain  or  pleasure. 

The  social  condition  varies  from  the  refinement  and  culture  of  the 
European  nations,  to  the  degradation  of  the  savage  who  roams  the 
tropical  forests,  or  burrows  in  the  earth  in  the  Arctic  islands. 

3.  Races  of  Men.  Notwithstanding  this  almost  infinite  diver- 
si  i,y  in  the  human  family,  certain  physical  features  and  mental  char- 
acteristics, which  have  remained  unchanged  from  a  time  anterior  to 
all  history,  are  common  to  great  groups  of  men.  These  different 
groups,  however,  are  not  so  sharply  defined  that  they  can  be  re- 
garded as  specifically  different ;  hence  they  are  denominated  races, 
instead  of  species,  like  the  distinct  groups  of  the  animal  kingdom. 

The  number  of  races  recognized  by  different  ethnologists,  varies 
according  to  the  number  of  common  features  which  each  regards  as 
essential  to  constitute  a  distinct  type.  Those  usually  taken  into 
account  are  the  stature  and  proportions  of  the  body  ;  the  form  of  the 
head  and  of  the  features  ;  the  color  of  the  skin,  and  the  appearance 
and  relative  abundance  of  the  hair  and  beard. 

The  races  are  often  designated  by  the  color,  the  most  obvious 
distinction,  though  far  from  being  a  fundamental  or  a  constant  one ; 
—  as  the  white  race,  the  yellow  race,  the  black,  the  red,  etc. 

II.  The  Geographical  Races. 


TYPICAL      M.A.If. 


AMERICAN 


MALAY.    • 
THE    RACES    OF    MEN 


1.  Number.  From  a  geo- 
graphical point  of  view,  six  dis- 
tinct races  are  recognizable, 
each  connected  with  one  of  the 
grekt  geographical  regions  of 
the  earth.  Each  shows,  through- 
out .all  its  branches,  a  common 
type,  coinciding  in  all  essential 
features  with  one  of  the  types 
recognized  as  distinct  by  the 
most  careful  ethnologists. 

2.  Location  and  Name. 
The  geographical  races  are  as 
follows :  — 

(1.)  The  Central,  or  White 
race,  occupying  western  Asia 
and  India,  Europe,  and  the 
Mediterranean  region  of  Africa, 
—  the  heart  and  centre  of  the 
great  mass  of  the  Old  World. 

(2.)  The  Mongolic,  or  1 
race,  occupying  the  who! 
eastern  Asia,  exclusive  of  India. 

(3.)  The  African,  or  I 
race  (from  the  Latin  n 
black),  occupying  all  of  A 
south  of  the  Sahara. 

(  I.)  The  Australian,  a,l> 
race,  occupying  Australia 
its  islands. 

(5.)  The  Malayan,  or  Brown  race,  occupying  the  Malay  Penin- 
sula, the  Indian  Archipelago,  ami  the  islands  of  the  Pacific  and  In- 
dian Oceans  ;  extending  from  Madagascar  to  the  easternmost  limits 


AUSTRALIAN. 


— " 


/ 


of   Polynesia,  ai 
Zealand. 

(6.)  The  Am 

New  World,  i 

It  will  lie  obset 
nents  which  form  t!-. 
one  at  the  north  .  an 

mote  continents, 

8.   CHABAC     tt»  CIG8 

their  tall  stati  il   t 

oval  head  and 

ruddy  cheeks  ;  fchi  ir  abundant  be* 

hair.     The  color     I'   ihc  skin  varii  .  irOJh  white  in 

the  European,  r  swarthy  in  the  Hindoos,  Arabs,  Eg 

thins,  and  Berb.  is,  who  live  on  the  borders  of  the  tropical  zone. 

This   is   fiii  denominated   the    Caucasian   race,  the  type 

being  found  in  its  greatest  beauty  in  the  Caucasus  and  the  moun- 
tain lands  of  I     .1   eapi  tiallj  in  Armenia  and  Persia.     (Portrait  4.) 


in. 
tingu. 


.  i.  form 

.i,riv  defined 

ly  more  than 

.:tore,  properly  be  dis- 


_m1',  and  the  Malayan  race,  less  strongly- 
uv-rs,  mayr  be  designated  the  secondary  races.    Of 


The  A, 
marked  thi 
these,  the  first  tv  Morigblic  rather  than  either  of  the 


ABYSSINIA 


SOUTH    DEC'CAN. 


WEST   SOUDAN.  11 


MOZAMBIQUE. 


12 


CAPE   OK    GOOD   HOPE  13 


IXUO-CIUNA 


CELEBES.  16 

MODIFICATION    OF    TYPES. 


i'EE.IEE  ISLANDS. 


SOUTH  AUSTRALIA. 


(2.)  The  Mongolic  peoples  are  characterized  by  their  short  stat- 
ure ;  their  broad  form  and  high  shoulders ;  their  round  head,  nar- 
rowing at  the  top,  and  wide,  flat  face  ;  their  small  chin,  and  prom- 
inent cheek  bones,  which  give  the  face  a  triangular  outline ;  their 
small,  deep-set,  oblique  eyes  ;  their  coarse,  straight  hair,  and  scanty 
In 'tad  ;  and  the  yellowish  color  of  their  skin.  (See  portraits,  3,  19, 
20,  21.)  This  type  is  found  most  clearly  marked  in  the  people  of 
the  great  plateau  of  Mongolia. 

(3.)  In  the  African  race,  the  stature  is  usually  of  average  height, 
but  the  figure  is  often  ungainly,  the  hands  and  feet  large  and  flat, 
and  the  gait  awkward.  The  head  is  narrow,  and  elongated  back- 
ward ;  the  forehead  is  low  and  retreating  ;  the  nose  broad  and  flat, 
tin'  cheek  bones  very  prominent,  the  jaws  projecting,  and  the  lips 
thick ;  and  the  hair  short  and  crisp,  or  woolly.  (See  portraits,  5, 
11,  12.) 

(4.)  The  Australians  show  a  general  resemblance  to  the  negro 
race,  yet  the  form  is  still  less  symmetrical,  often  gaunt  and  meagre  ; 
and  the  features  more  irregular.  The  color  is  a  livid  grayish  black; 
the  hair  thick  and  waving,  or  bushy  ;  the  beard  abundant,  and  the 
eyes  very  deep-set,  black,  and  piercing.     (See  portrait,  8.) 

(  5.)  The  Malayan,  race  have,  in  general,  the  features  of  the  Mon- 


other  primary  races,  and  may  be  distinguished  as  the  Mongoloid 
types.  The  Australian  is.  Negroid,  with  scarce  a  feature;  similar  to 
either  the  White  or  the  Yellow  race. 


III.  The  White  Race  the  Normal,  or  Typical,  Race. 

1.  The  typical  MAN  —  as  exhibited  in  the  unrivaled  works  of 
the  ancient  sculptors  (see  the  Apollo  Belvedere,  1,  2)  —  is  distin- 
guished by  perfect  regularity  of  features,  and  harmony  in  all  the  pro- 
portions of  the  figure,  securing  agility  and  strength  in  the  highest 
degree,  with  the  utmost  beauty  and  grace. 

The  head  is  oval,  symmetrical,  and  well  poised,  its  form  showing  the  proper  bal- 
iiiiic  of  all  the  faculties,  with  the  just  subordination  of  the  lower  to  the  higher. 
The  face  is  a  symmetrical  oval,  and  is  divided  into  three  equal  parts  by  the  line 
of  the  eyes  and  the  base  of  the  nose.  The  ryes  are  large,  well  formed,  and  sepa- 
rated by  a  space  equal  to  the  length  of  the  eye.  The  mouth  is  small  and  finely  cut, 
the  lips  gracefully  curving  from  the  centre  The  stature  is  tall,  lithe,  and  graceful, 
the  shoulders  not  disproportionately  wide  nor  narrow ;  while  the  distance  measured 
by  the  extended  arms  is  equal  to  the  entire  height  of  the  body. 

These  ideal  harmonies  of  proportion  are  realized  in  many  indi- 
viduals among  the  nations  inhabiting  the  mountain  lands  of  Iran,  in 
western  Asia,  —  that  region  which  revelation,  the  traditions  of  (he 


variatious  fn,. 
derance  of  thf>  io%> 
aud  moral,  they  indie" 

2.  Gradual  Modi 
depart  from  Iran,  the  geoj:  >:  .  ilarity 

of  features  diminishes,  and  the  ha  isappears. 

This  gradual  transition  of  type  is  elearli  .a-  successive 

peoples  met  with  in  all  directions  from  this  centre. 

Passing  southward  we  first  meet  the  Arab,  belonging  unquestion- 


yet  beautiful  Hindoos, 
,!),  and  the  Siamese  of 
le  true  White  and  Mon- 
ti i  the  more  distant  Ma- 
>>  the  peninsula  and  the 
differ   materially  in  the 

the  true  Malay  with  the 
ing  from  New  Guinea  to  the 
still  possess  some  advantages 
true  Australian  type  (8),  we 
come  to  tlie  so-.,,   ..  and  Tasmanians    (18),  among  the 

ugliest  of  mankind,  with    gaunt  body,    meagre    members,  bending 
knees,  hump  back,  and  projecting  jaws. 

Passing  northeastward  to  the  extremity  of  Asia  we  observe  almost 
insensible  transitions,  through  the  Tartars  (19)  and  other  Turanian 
people  (see  Map)  —  some  of  whom  are  hardly  distinguishable  from 


TURAN 


ciiiwa 


UTAH. 


24 


NEW  MEXICO 


EASTERN   BRAZIL 


n 


ANDES   OV    I'ERU.     27 


T1ERRA   DEL   FUEGO.        28 


MODIFICATION   OF    TYPES. 


ably  to  the  white  race,  but  his  head  is  less  symmetrical,  while  his 
complexion  varies  with  the  climate  to  tawny  and  even  to  black. 

Next  are  the  transition  types  of  Abyssinia  (portrait  9)  and  Nubia 
(10),  with  features  still  comparatively  regular ;  but  with  a  swarthy 
or  black  color,  closely  curling  hair,  and  an  increasing  resemblance  to 
the  negro.  The  inhabitants  of  west  Soudan  (11),  show  the  true 
negro  type  ;  yet,  while  the  skin  is  black  and  the  features  coarse,  the 
expression  of  the  face  still  indicates  a  lively  intelligence.  The  same 
general  characteristics  are  shared  by  the  tribes  of  equatorial  Africa 
and  of  Mozambique  (12)  ;  but  in  the  more  southerly  regions  are 
the  Hottentots  and  the  Bushmen,  who  are  among  the  most  degraded 
types  of  humanity. 


the  White  race,  —  to  the  true  Mongols  of  the  plateau  (20). 

Beyond,  the  Chinese  (21)  are  still  true  Mongolians,  but  the  Jap- 
anese are  less  strongly  marked.  The  Kamchadale  (22)  is  clearly  a 
transition  type  through  which  we  reach  the  Esquimaux  (22),  of 
the  Aleutian  Islands,  and  the  Arctic  lands  of  America. 

Passing  southward  through  America,  we  meet,  in  the  middle  lati- 
tudes, the  Indians  of  the  Rocky  Mountains  (6,  24,  25),  who  are  a 
comparatively  noble  type,  often  tall  and  symmetrical  in  form.  In 
the  tribes  of  South  America  (26,  27)  we  observe  an  increasing  de- 
formity and  ugliness ;  while  the  Pecherays  of  Tierra  del  Fuego  (28) 
are  the  most  misshapen,  the  farthest  from  any  culture,  the  most 
wretched  of  the  inhabitants  of  the  New  World. 


QUESTIONS  ON  THE  MAP  OF  THE  RACES. 


What  branches  of  the  Mongolic  race  people  the  eastern  shores  and  islands  of  Asia? 
What  branches  people  the  Arctic  plains?    What  peoples  intermediate  between  the  latter  and 
the  Esquimaux  of  America? 

Where  are  the  true  Mongols  found  ?     What  branch  of  their  race  south  of  them ? 

What  peoples  are  included  in  the  Turanian  family? 

What  Turanian  peoples  in  Europe  and  Asia  Minor? 

Name  the  Asiatic  branches  of  the  Indo-European  family;  the  European  branches. 

What  part  of  Europe  does  each  of  these  great  branches  occupy  ? 

Name  the  Semitic  peoples  of  northern  Africa. 


What  portions  of  the  New  World  are  occupied  by  Indo-Europeans  ?  Of  Africa  ?  Of  Aus- 
tralia ? 

What  are  the  three  principal  branches  of  the  Malay  race  ? 

What  are  the  eastern  branches  of  the  American  race  in  North  America?  The  western 
branches  ? 

What  are  the  principal  branches  of  this  race  in  South  America  ? 

What  mixed  races  in  South  America  and  the  southern  part  of  North  America? 

What  race  intermediate  between  the  Malays  and  the  Australians  ? 

What  races  in  North  Africa  intermediate  between  the  whites  and  the  true  negro? 

What  mixed  races  in  eastern  Africa?    What  part  of  Africa  is  peopled  by  Hottentots?      , 


118 


CONCLUSION— THE   TERRESTRIAL   CONTRASTS. 


II.— UNITY  AND   CULTURE  OF  THE  RACES. 

I.  Unity  of  Mankind. 

1.  Evidences  of  Unity.  A  comparison  of  the  different  tribes 
and  races  of  men,  reveals  the  fact  of  ^gradual  modification  of  types, 
on  every  side  of  the  central  or  highest  raceVuntil,  by  insensible  de- 
grees, the  lowest  and  most  degraded  forms  of  humanity  are  reached. 

Again :  in  the  central  race,  —  among  the  individuals  of  which 
there  is  greater  diversity  in  form,  features,  temperament,  and  men- 
tal characteristics,  than  in  any  other, — there  are  persons  of  pure 
blood  who  show,  in  a  less  degree,  almost  every  distinguishing  feature 
of  each  of  the  lower  races. 

These  facts  establish  a  bond  of  union  among  all  the  varieties  of 
mankind,  however  remote  they  may  appear  to  be  from  the  most 
noble  type.  They  also  seem  to  indicate  that  the  White  is  the  nor- 
mal race,  from  which  the  others  have  gradually  deviated. 

2.  The  Law  of  Perfection  of  Type,  in  man,  therefore,  forms 
an  exception  to  that  observed  in  the  lower  orders  of  creation.  (Page 
106,  Topic  I.)  The  human  family  appears  in  its  highest  physical 
perfection,  not  within  the  Tropics,  but  in  the  Temperate  Zone,  in 
western  Asia,  the  geographical  centre  of  the  Old  World. 

The  type  degenerates  gradually,  with  increasing  distance,  in  all 
directions  from  this  geographical  centre  ;  until,  in  the  remotest  re- 
gions of  the  globe,  are  found  the  ugliest,  and  the  most  deformed 
specimens  of  the  human  family. 

The  degree  of  perfection  of  the  type  is  therefore  proportioned,  not 
to  intensity  of  material  agencies,  but  to  distance  from  the  central 
and  highest  race,  irrespective  of  climatic  conditions.  The  degree  of 
culture  of  the  races  also  varies  in  the  same  order.  The  central  race 
is  the  race  of  culture  and  progress,  both  now  and  in  all  past  ages. 

II.  The  White  Race. 

1.  BRANCHES.  This  race  is  divided,  on  the  basis  of  language  and  mental  char- 
acteristics, into  three  great  branches,  designated  the  Hamitic,  Semitic,  and  Japhetic, 
or  Indo-European,  families,  each  of  which  has  had  its  especial  function  in  history. 

The  Hamitic  family  were  the  ancient  people  of  Palestine,  the  Nile  basin,  and 
the  shores  of  the  Arabian  Sea  and  Persian  Gulf.  They  have  either  passed  away 
or  have  so  blended  with  their  Semitic  and  Japhetic  conquerors  as  to  be  scarcely 
disjinguishable. 

The  Semitic  family,  who  first  appear  on  the  upper  Euphrates  and  in  Syria, 
spread  over  the  larger  part  of  Arabia  and,  later,  over  northern  Africa. 

The  Indo-European  family,  whose  original  seats  appear  to  have  been  on  the 
northern  borders  of  Iran,  spread  over  this  entire  table-land,  and  westward,  through 
Europe ;  while  a  small  branch  went  eastward  into  India. 

2.  Their  Work.  The  Hamites  and  Semites  were  the  earliest  to  gather  into 
communities  with  organized  governments,  and  to  cultivate  the  arts  and  learning. 

The  Hamites,  a  practical  and  inventive  people,  developed  especially  in  the  direc- 
tion of  material  civilization ;  though  they  made  comparatively  high  attainments 
in  literature  and  in  mathematical  science. 

The  Semites  were  the  guardians  of  the  ancient  revelations.  Though  contrib- 
uting less  than  the  Hamites  to  the  material  progress  of  the  race,  they  gave  to  the 
world  in  succession  -the  simple  religion  of  the  patriarchs,  the  Mosaic  ritual,  and 
Christianity,  the  fundamental  principle  of  modern  civilization.  Later,  Moham- 
medanism had  its  origin  among  the  same  people. 

The  Indo-Europeans,  though  later  in  entering  upon  their  career,  and  deriving 
the  germs  of  their  civilization  from  the  other  two  families,  have  shown  themselves 
to  be  emphatically  the  people  of  progress. 

The  Greco-Latin  branch,  in  southern  Europe,  carried  the  heathen  civilization 
of  antiquity  to  its  highest  perfection  ;  and  the  Christian  civilization  of  modern 
times  finds  its  highest  expression  among  the  northern  branches  of  the  same  family. 
They  now  possess  the  entire  New  World,  the  continent  of  Australia,  and  the  great 
peninsula  of  India ;  and  have  established  themselves  in  various  parts  of  Africa  and 
upon  the  islands  of  the  sea.     (See  map.) 


III.  Mongolic  and  Negro  Races.  » 

1.  The  Mongolic  Race  is  more  numerous  than  any  other,  and,  including  the 
various  Mongoloid  types,  more  widely  dispersed  than  all  others  together.  This  race 
very  anciently  attained  a  comparatively  high  degree  of  civilization,  and  founded  a 
powerful  monarchy  in  China.  They  have,  however,  contributed  little  to  the  prog- 
ress  of  mankind  in  general,  owing  to  their  isolation,  their  jealousy  of  foreign 
nations,  and  the  policy  of  non-intercourse  so  rigidly  observed  by  them  even  to  the 
present  time. 

The  Japanese,  though  less  ancient  as  a  nation  than  the  Chinese,  surpass  them 
in  culture  ;  and  are  now  entering  upon  a  new  era  of  pi  ogress  in  reorganizing  theiz 
social  system  on  the  basis  of  modern  ideas. 

2.  The  Negro  Race  have,  by  themselves,  made  only  the  first  steps  in  civili- 
zation, and  the  great  mass  are  still  "in  the  savage  state.  Where  they  have  been 
brought  under  the  influence  of  cultured  nations,  however,  they  have  shown  them- 
selves capable  of  a  high  degree  of  progress. 

A  colony  of  American  negroes  have  successfully  organized  the  Republic  of  Li- 
beria, on  the  west  coast  of  Africa,  which  gives  promise  of  doing  an  important 
part  in  the  work  of  Christianizing  and  civilizing  this  great  and  rich  continent. 


IV.  Secondary  Races. 

1.  The  Secondary  Races  have  contributed  nothing  to  the  present  condition 
of  mankind  ;  and  none  of  the  existing  branches  have  taken  more  than  the  first 
steps  in  civilization,  except  under  the  influence  of  the  White  or  Mongolic  races. 

2.  Ancient  American  Civilization.  The  inhabitants  of  the  table-lands  of 
Mexico,  and  of  the  high  plateaus  of  the  Andes,  had,  at  the  discovery  of  America, 
populous  and  rich  cities,  organized  governments  and  religious  systems,  and  great 
skill  in   some  of  the  arts,  especially  in   the  working  of  gold,  silver,  and   bronze. 

There  are  ruins  of  a  still  higher  and  more  ancient  civilization,  both  here  and  in 
the  highlands  of  Central  America ;  but  of  the  origin  of  these  cultured  peoples 
nothing  is  known  definitely.  Certain  peculiarities  in  their  customs,  and  in  the 
works  of  art  found  in  their  tombs  and  ruins,  point  to  an  Asiatic  origin  for  the 
Peruvian,  and  a  Semitic  or  Egyptian  for  the  Mexican  civilization. 


III.  —  CONCLUSION. 


I.  — THE  TERRESTRIAL  CONTRASTS. 

I.  Introduction. 

The  three  grand  contrasts  observed  in  the  arrangement  of  the 
land  masses  upon  the  globe  (page  21),  reappear  in  the  climates, 
through  which  they  exert  a  marked  influence  upon  the  character  and 
distribution  of  every  order  of  life. 

The  continental  and  oceanic  worlds  present  a  contrast  of  geograph- 
ical elements,  —  the  land,  and  the  water,  the  most  general  and  fun- 
damental of  all.  The  contrast  of  the  eastern  and  the  western  world 
is  one  of  area  and  structure.  The  northern  and  the  southern  world 
show  essentially  a  contrast  of  climate. 


II.  Continental  and  Oceanic  Worlds. 

1.  The  Oceanic  World,  the  world  of  uniformity,  is  also  the 
world  of  inferiority.  The  life  predominating  by  quantity  is  that  of 
the  sea,  —  vastly  lower,  both  vegetable  and  animal,  than  that  of  the 
land.  Australia  and  the  oceanic  islands,  alike,  lack  all  the  higher 
types,  whether  of  plants  or  of  animals,  and  are  peopled  only  by  the 
lower  races. 

2.  The  Continental  World,  characterized  by  diversity  in  all 
its  conditions,  is  the  world  of  superiority  both  in  the  realm  of  nature 
and  that  of  man.  It  is,  however,  not  in  the  heart  of  the  continents 
that  the  highest  development  is  found ;  but  in  the  maritime  zone,  or 
zone  of  contact  of  the  continental  and  oceanic  worlds,  along  the 
coasts,  and  in  the  great  continental  islands. 


THE  CONTINENTS    OF  HISTORY. 


119 


3.  The  Maritime  Zone.  Advantages.  Here  the  vigor  of  the 
continents,  their  variety  of  reliefs,  soil,  and  temperature,  is  blended 
■  with  the  moisture  of  the  seas  ;  and  the  extremes  of  the  continental 
climate  (page  73)  are  tempered,  without  being  reduced  to  the  same- 
ness of  the  oceanic. 

Here,  too,  the  great  highway  of  the  seas  permits  that  constant  in- 
terchange, both  of  commodities  and  of  ideas,  which  seems  essential 
to  the  development  of  human  society  ;  yet  which,  in  the  heart  of  the 
continents,  is  more  difficult,  sometimes  almost  impossible. 

Life.  We  have  seen  that  the  highest  types  of  the  animal  world, 
and  the  most  varied  forms  of  the  vegetable,  with  many  of  the  most 
precious  of  vegetable  productions,  are  found  in  the  islands  of  the 
Indian  archipelago,  on  the  margin  of  the  oceanic  hemisphere. 

In  the  same  zone  of  contact,  we  find  the  highest  civilizations  of 
eastern  Asia,  —  in  Japan,  China,  and  India  ;  while  the  shores  of  the 
Mediterranean  were  the  theatre  of  the  most  cultured  nations  of  an- 
tiquity ;  as  those  of  the  Atlantic  are  the  scenes  of  the  highest  devel- 
opment and  activity  at  the  present  day. 

III.  Old  and  New  Worlds. 

1.  The  New  World,  —  narrow,  elongated,  isolated  between  two 
great  oceans ;  with  a  preponderance  in  its  structure  of  plains  which 
are  everywhere  open  to  warm  sea  winds,  —  is,  in  the  main,  charac- 
terized by  medium  temperatures,  abundant  moisture,  and  the  great- 
est luxuriance  and  power  of  vegetable  life. 

In  its  fauna  the  lower  types  predominate  ;  and  the  native  people 
are  essentially  the  men  of  the  forest,  a  race  of  hunters,  without  do- 
mestic  animals,  and  with  only  the  rudiments  of  agriculture  here  and 
there. 

2.  The  Old  World,  —  vast,  compact,  composed  of  the  largest 
two  land  masses  (Asia-Europe  and  Africa),  closely  crowded  to- 
gether, from  a  large  part  of  which  the  sea  winds  are  almost  excluded, 
— is  characterized  by  the  greatest  extremes  of  temperature;  and  by 
a  lack  of  moisture  and  poverty  of  vegetation  over  immense  areas  of 
the  interior.  It  is  the  domain  of  the  higher  orders  of  animal  life, 
especially  of  animals  capable  of  domestication;  and  of  the  civilized 
and  progressive  races. 

IV.  Northern  and  Southern  Worlds. 

1.  The  southern  continents,  —  lying  mainly  in  the  tropical 
zone,  where  all  the  conditions  that  stimulate  physical  life  are  most 
powerful,  and  where,  with  few  exceptions,  man  has  remained  at  the 
bottom  of  the  social  scale,  —  may  be  designated  the  continents  of 
nature.  Each  has  its  own  especial  character,  wherein  the  influence 
of  every  distinguishing  feature  of  the  continent  is  seen. 

In  South  America,  —  the  tropical  continent  of  the  Western 
World,  and  especially  the  continent  of  plains,  —  all  the  characteris- 
tics of  the  New  World  are  exhibited  in  an  exaggerated  degree.  It 
is  preeminently  the  realm  of  vegetable  life,  where  we  find  the  largest, 
the  most  dense,  and  the  most  varied  forests,  and  the  greatest  devel- 
opment of  foliage  on  the  face  of  the  earth. 

Africa.  —  the  tropical  continent  of  the  Eastern  World,  and  the 
continent  of  plateaus, — has,  in  an  extreme  degree,  the  dry  con- 
tinental climate  of  the  Old  World.  It  is,  above  all,  the  realm  of 
the  nobler  animals,  of  the  mammalia,  —  the  highest  division  of  the 
animal  world,  —  which,  by  their  number,  their  variety,  their  size 
and  strength,  give  the  African  fauna  its  distinctive  character. 

Australia,  the  only  sub-tropical  continent,  and  the  most  isolated, 


the  smallest,  and  the  least  varied  of  all,  is  the  only  one  which  pre- 
serves to  a  great  extent  the  ancient  forms  of  plants  and  animals. 
Its  isolation,  size,  and  structure,  as  well  as  its  fauna  and  flora,  find 
their  parallel  in  the  other  continents  in  the  middle  geological  ages. 

2.  The  Northern  Continents,  may  properly  be  designated  the 
continents  of  history.  Less  richly  endowed  with  those  elements 
which  foster  the  life  of  nature,  they  possess  all  the  conditions  most 
favorable  for  the  development  and  progress  of  the  races  inhabiting 
them  ;  and  each  was  apparently  designed,  from  the  beginning,  for 
the  performance  of  a  peculiar  part  in  the  education  of  mankind. 


II.  — THE   CONTINENTS    OF  HISTORY. 


I.  Asia. 


1.  Characteristics.  Asia  is  the  largest  of  the  continents,  the 
most  central,  the  only  one  with  which  all  the  others  are  closely  con- 
nected ;  and  the  one  whose  different  physical  regions  show  the 
strongest  contrasts,  and  are  separated  by  the  greatest  barriers. 

It  has  the  loftiest  mountains,  the  highest  and  most  extended  pla- 
teaus, the  greatest  plains,  and  the  most  numerous  river  systems ; 
with  all  climates,  from  the  hottest  to  the  coldest,  from  the  dryest  to 
the  most  moist.  It  has,  also,  a  large  number  of  useful  plants,  and 
of  animals  capable  of  domestication  ;  together  with  an  abundance 
of  both  the  useful  and  the  precious  metals. 

2.  Its  Function.  This  great  and  strongly  marked  continent  is 
the  continent  of  origins.  The  human  family,  its  races  and  civiliza- 
tions, and  the  systems  of  religion  which  rule  the  most  enlightened 
nations,  all  had  their  beginning  here. 

By  the  great  diversity  of  its  physical  features  and  climate,  and 
the  strong  barriers  isolating  them  one  from  another,  Asia  was  ad- 
mirably fitted  to  promote  the  formation  of  a  diversity  of  races  ;  while 
its  close  connection  with  the  other  continents  facilitated  their  disper- 
sion throughout  the  earth. 

Its  alluvial  plains,  with  their  well-defined  boundaries  of  moun- 
tains or  deserts,  and  their  rich  soil,  —  covered  annually  by  overflow- 
ing rivers  with  a  fruitful  loam,  and  so  easily  tilled  that  a  plough  was 
scarcely  needed,  —  seem  to  have  been  especially  adapted  to  foster 
the  progress  of  a  race  still  in  its  infancy. 

The  abundance  of  their  resources,  developed  by  agriculture, 
allowed  the  congregation  of  great  numbers  of  men  upon  the  same 
area,  and  thus  favored  the  formation  of  organized  governments  ; 
while  the  conflict  with  the  overflowing  rivers,  the  necessity  of  irri- 
gation, and  the  alternation  of  the  seasons,  incited  forethought,  and 
gave  birth  to  the  useful  arts  and  the  sciences  of  observation. 

3.  Centres  of  Culture.  The  four  great  alluvial  plains  of 
Asia,  —  those  of  China  and  of  the  Amoo  Daria,  in  temperate  re- 
gions ;  of  the  Euphrates  and  Tigris  in  the  warm-temperate  ;  and  of 
the  Indus  and  Ganges  under  the  tropic,  —  with  the  Nile  valley  in 
Africa,  were  the  theatres  of  the  most  ancient  civilizations  known  to 
history  or  tradition. 

In  the  remotest  antiquity  each  of  these  regions  became  the  seat  of 
a  distinct  nation,  with  a  material  and  intellectual  development,  a  re- 
ligion, and  a  social  organization  peculiar  to  itself  ;  and  together  they 
formed  the  five  great  centres  of  the  primitive  culture  of  the  race. 

China  and  India,  isolated  from  each  other,  and  from  the  West,  by 
almost  impassable  mountains  and  desert  plateaus,  have  left  scarce  a 
trace  upon  the  subsequent  progress  of  mankind  ;  but  the  others,  in 
greater  proximity  to  Europe,  became  the  parents  of  the  higher  cul- 
ture of  ancient  Greece  and  Rome,  and,  through  them,  of  modern 
civilization. 


120 


THE   CONTINENTS    OF   HISTORY- 


LangittU*.    lOU     Wktt     At.//. 


II.  Europe. 

1.  Characteristics.  Europe  shows  a  diversity  of  structure  even 
greater  than  that  of  Asia ;  but  with  smaller  areas,  more  moderate 
forms  of  relief,  less  extreme  contrasts  of  climate,  a  more  generally 
fertile  soil,  and  every- 
where an  abundance 
of  the  most  useful 
minerals ;  while  the 
relative  extent  of  its 
coast  line  —  its  mari- 
time zone —  is  greater 
than  that  of  any  other 
continent. 

This  continent  is 
especially  fitted,  by  its 
diversity,  to  foster  the 
formation  of  distinct 
nationalities,  each  de- 
veloping in  an  especial 
direction.  Moreover, 
the  proximity  of  these 
nations  one  to  another, 
the  greater  facility  of 
communication  be- 
tween them,  and, 
above  all,  the  com- 
mon highway  of  the 
sea,  nowhere  very  dis- 
tant, facilitates  mutual  intercourse,  the  lack  of  which  arrested  the 
progress  of  the  civilizations  of  Asia. 

2.  Centres  op  Progress.  In  Asia  it  is  in  the  great  inland 
plains,  on  the  banks 
of  the  rivers,  that 
civilization  first  shows 
itself.  In  Europe 
it  is  in  the  peninsulas 
and  islands,  on  the 
margins   of    the   seas 

—  the  regions  most  ac- 
cessible to  influences 
from  without  —  that 
the  most  ancient  states 
are  founded  ;  for  not 
only  her  inhabitants, 
but  the  germs  of  her 
culture,  were  derived 
from  Asia. 

3.  F  UNCTIONS. 
Though  not  the  conti- 
nent  of  origins,  Eu- 
rope is  emphatically 
the  continent  of  de- 
velopment. The  In- 
do-European race  — 
the  people  of  progress 

—  find  their .  fullest  expansion  and  activity,  not  in  their  original 
seat  in  Iran,  but  in  Europe,  whence  they  are  spreading  over  all 
quarters  of  the  globe.  The  arts  and  learning  of  antiquity  attained 
their  highest  development,  not  in  western  Asia  and  Egypt,  the  places 
of  their  origir,  but  in  Greece  and  Rome. 


Christianity,  also,  only  germinated  in  western  Asia.  Trans- 
planted to  Europe,  it  gradually  attained  its  full  development,  and 
became  the  foundation  on  which  is  reared  the  vast  and  noble  edifice 
of  modern  civilization. 


A  Explanation. 

BW  .o'  •  The  ft'»wre;»  ^ree  in  sqiutre 

..miles,  "the  are*  of   fke  river 
Slav  n;^6£p<  c„„,;d  y,}  ,?c-h  oll.«r. 


HI.  America. 


THE  UNITED  STATES.      RIVER  BASINS 


THE  UNITED    STATES.      VEGETATION. 


1.  Character- 
istics. America,  dif- 
ferent in  position, 
structure,  and  climatic 
conditions,  from  both 
the  other  northern 
continents,  seems  des- 
tined to  play  a  part  in 
the  history  of  man- 
kind unlike  that  of 
Europe  and  Asia, 
though  not  less  noble 
than  either. 

The  structure  of 
this  continent  (page 
31)  is  characterized 
by  a  unity  and  sim- 
plicity as  striking  as 
is  the  diversity  of  Eu- 
rope. 

Few  and  vast  phys- 
ical regions  —  the 
western  highlands  and  the  eastern  plains,  the  northern  and  the 
southern  slope  —  with  comparatively  slight  barriers  between  them, 
present  a  marked  contrast  to  the  multiplicity  of  areas,  with  clearly 

defined  natural  bound- 
aries, which  charac- 
terize Asia-Europe. 

Again,  great  river 
systems,  whose  basins, 
narrowed  to  a  mere 
doorway  near  the  sea 
(see  Map  of  River 
Basins  of  U.  <S'.), 
spread  wide  in  the  in- 
terior,  establish  an 
easy  communication! 
almost  everywhere; 
between  the  east  and 
the  west,  the  north 
and  the  south. 

In  its  climate,  those  •' 
contrasts  in  tempera- 
ture which  are  so  vio- 
lent in  Asia,  and  still 
prevail  in  Europe,  are 
obliterated.     The  cole 
zone   of   the   nortl 
passes  by  insensible 
degrees  into  the  warm  zone  of  the  south ;  while  in  the  western  half 
the  bracing  climate  of  the  temperate  regions  is  prolonged  into  the  j 
tropical,  by  the  greater  elevation  of  the  highlands  towards  the  south. 
The  east  and  the  west  differ  little  in  temperature,  the  elevation  of 
the  latter  being  counterbalanced  by  the  exclusion  of  the  polar  winds, 


THE  CONTINENTS   OF  HISTORY. 


121 


and  the  free  sweep  of  the  return  trades  over  its  surface.  Salt  Lake 
City,  for  example,  on  the  same  parallel  with  New  York,  though  more 
than  4,000  feet  above  it,  has  the  same  average  annual  temperature, 
which  does  not  differ  greatly  from  that  of  the  corresponding  latitude 
on  the  Pacific  coast. 

The  chief  contrast  of  the  continent  is  that  of  the  coasts  and  the 
interior,  the  maritime  and  the  continental  climates  ;  but  even  this  is 
softened,  the  great  Gulf  of  Mexico  carrying  the  maritime  zone  almost 
into  the  heart  of  the  continent ;  while  the  warm  equatorial  wind 
spreads  its  wealth  of  vapors  over  the  interior  plains  at  the  north  and 
east.  The  high  plateaus  of  the  west  alone  are  arid. 
•  The  differences,  in  surface  and  climate,  sufficient  to  create  diver- 
sity in  industries  and  in  the  products  of  the  soil,  are  not,  as  in  Asia, 
marked  enough  to  give  rise  necessarily  to  entirely  different  modes  of 
life  among  the  inhabitants,  and  to  create  antagonistic  interests.  By 
fostering  internal  commerce,  they  unite  rather  than  separate  the 
people  of  the  several  regions. 

Finally,  the  oceanic  position  of  America  secures  its  commercial 
prosperity,  and  prepares,  at  the  same  time,  the  means  of  its  influ- 
ence on  the  world. 

2.  The  most  Characteristic,  as  well  as  the  most  valuable,  part 
of  America,  is  the  noble  domain  of  the  United  States.  Between  the 
cold,  semi-arctic  northern  slope,  and  the  tropical  climes  of  the  south, 
it  is  situated  wholly  in  temperate  latitudes,  with  a  climate  the  most 
favorable  for  the  active  life  of  civilized  communities. 

In  the  eastern  half  are  fertile  plains  and  valleys,  teeming  with 
agricultural  wealth,  or  covered  with  forests ;  in  the  west,  pasture 
lands,  or  plateaus  and  mountains  rich  in  silver  and  gold.  On  the 
north  are  corn  lands,  water-power,  and  inexhaustible  mines  of  coal, 
copper,  and  iron  ;  on  the  south,  tobacco,  cotton,  rice,  and  cane. 

This  diversity  of  resources  creates  the  necessity  for  constant  inter- 
course, which  is  facilitated  to  the  utmost  by  the  vast  river  systems, 
the  great  length  of  coast  line,  and  the  absence  of  barriers  between 
the  different  regions.  Thus  the  unity  of  the  entire  people  is  pro- 
moted, and  the  formation  of  local  nationalities  is  checked. 

Again,  the  agricultural  wealth  of  the  eastern  half,  flowing  natu- 
rally to  the  Atlantic  ports,  is  essential  to  the  overcrowded  industrial 
nations  of  western  Europe  ;  and  brings  the  youthful  and  vigorous 
American  people  into  constant  contact  with  European  culture,  ac- 
quired through  long  ages  of  progress. 

The  mineral  treasures  of  the  Pacific  slope,  attracting  a  large  and 


energetic  population  to  that  less  fertile  side  of  the  continent,  pre- 
pare the  way  for  intercourse  with  the  long  dormant  nations  of  east- 
ern Asia ;  while  from  the  ports  of  both  oceans  there  is  a  ready  access 
to  the  lower  races  in  the  continents  of  the  south. 

3.  Functions.  Nowhere  do  we  find  in  America  those  local  cen- 
tres, each  having  a  strongly  marked  individuality,  which  fostered 
the  progress  of  the  race  in  its  infancy  and  its  youth ;  but  every- 
where provision  is  made  for  mutual  intercourse,  a  common  life,  and 
the  blending  of  the  entire  population  into  one.  Evidently  this  con- 
tinent was  not  designed  to  give  birth  and  development  to  a  new  civ- 
ilization ;  but  to  receive  one  ready-made,  and  to  furnish  to  the  culti-  ( 
vated  race  of  the  Old  World  the  scene  most  worthy  of  their  activity. 

Its  vast  plains,  overflowing  with  natural  wealth,  are  turned  to- 
wards Europe,  and  its  largest  rivers  discharge  into  the  Atlantic ; 
while  its  lofty  mountains,  and  less  fertile  lands,  are  removed  far  to- 
wards its  western  shores.  Thus  it  seems  to  invite  the  Indo-European 
race,  the  people  of  progress,  to  new  fields  of  action ;  to  encourage 
their  expansion  throughout  its  entire  territory,  and  their  fusion  into 
one  nation ;  while  it  opens  for  them  a  pathway  to  all  the  nations  of 
the  earth. 

America,  therefore,  with  her  cultured  and  progressive  people,  and 
her  social  organization,  founded  upon  the  principle  of  the  equality 
and  brotherhood  of  all  mankind,  seems  destined  to  furnish  the  most 
complete  expression  of  the  Christian  civilization ;  and  to  become 
the  fountain  of  a  new  and  higher  life  for  all  the  races  of  men. 

IV.  Conclusion. 

Each  continent  has,  therefore,  a  well-defined  individuality,  which 
fits  it  for  an  especial  function.  The  fullness  of  nature's  life  is  typi- 
fied by  Africa,  with  its  superabundant  wealth  and  power  of  animal 
life ;  South  America,  with  its  exuberance  of  vegetation  ;  and  Aus- 
tralia, with  its  antiquated  forms  of  plants  and  animals. 

In  the  grand  drama  of  man's  life  and  development,  Asia,  Europe, 
and  America  play  distinct  parts,  for  which  each  seems  to  have  been 
admirably  prepared. 

Truly  no  blind  force  gave  our  Earth  the  forms  so  well  adapted  to 
perform  these  functions.  The  conclusion  is  irresistible  —  that  the 
entire  globe  is  a  grand  organism,  every  feature  of  which  is  the  out- 
growth of  a  definite  plan  of  the  all-wise  Creator  for  the  education  of 
the  human  family,  and  the  manifestation  of  his  own  glory. 


REVIEW   OF  PART  V. 


Life  in  Nature.  I. 

(Page  97.)  How  is  the  system  of  life  in  nature  represented?  What  is  the  especial  function 
of  plants  ?     Prepare  an  analysis  of  Section  I. 

II.  What  are  the  conditions  of-the  development  of  vegetable  life  ?  Where  is  vegetable  life 
possible  with  an  average  temperature  below  the  freezing  point?  Why?  (100.)  What  is  the 
mean  temperature,  and  the  characteristic  vegetation,  of  the  several  zones?  What  useful  plants 
belong  to  each?    Prepare  an  analysis  of  Section  II. 

III.  (101.)  How  do  the  three  northern  continents  compare  in  the  character  of  their  flora? 
What  especially  distinguishes  North  America  from  the  others?  What  cultivated  plants  are 
derived  from  western  Asia?  Describe  the  flora  of  the  Indian  peninsulas  and  Archipelago. 
What  is  the  characteristic  vegetation  of  Arabia  ?     Prepare  an  analysis  of  Section  III. 

IV.  (102.)  What  effect  has  increasing  altitude  upon  vegetable  life?  Why?  Describe  the 
successive  regions  of  plants  upon  the  Himalaya  Mountains.  How  does  the  flora  near  the  snow 
line  on  the  Alps  compare  with  that  on  the  Andes?    Why?     Prepare  an  analysis  of  Section  IV. 

V.  (104.)  Describe  the  flora  of  equatorial  Africa ;  of  northern  Africa;  of  southern  Africa. 
What  are  the  characteristics  of  the  South  American  flora?  To  what  are  they  due?  Describe 
the  tropical  forests.  What  useful  plants  are  indigenous  in  tropical  America?  (105.)  Why 
has  Chili  so  inuili  richer  vegetation  than  the  western  slope  of  Bolivia  and  Peru ?  Prepare  an 
analysis  of  Section  V. 

VI.  (106.)  Explain  the  diagram  which  illustrates  the  aspects  of  nature.  What  is  the  general 
law  of  the  development  of  life  in  nature?    What  are  the  characteristics  of  the  tropical  zone, 


in  regard  to  both  vegetable  and  animal  life  ?    Of  the  warm  zone  ?    Of  the  temperate  zone  ? 
Of  the  cold  zones  ?    Prepare  an  analysis  of  Section  VT. 

VII.  (108.)  What  is  the  extent  of  the  resemblance  in  the  fauna  of  the  northern  continents? 
What  animals  are  especially  characteristic  of  North  America?  Of  Asia?  Prepare  an  analysis 
of  Section  VII. 

VIII.  (109.)  What  is  the  general  character  of  the  African  fauna?  What  animals  are  espe- 
cially characteristic  of  the  arid  regions  ?  Describe  the  fauna  of  equatorial  Africa.  What  classes 
of  animals  are  especially  characteristic  of  South  America?  (110.)  What  is  the  general  char- 
acter of  the  Australian  fauna?  What  are  the  most  characteristic  animals?  Prepare  an  analy- 
sis of  Section  VIII. 

Provision  for  Human  Life.  I. 

(111.)  How  do  the  materials  employed  as  food  vary  in  the  different  zones,  and  whence  are 
they  derived?  To  what  extent  are  materials  for  raiment  provided  in  nature?  (112.)  What 
materials  are  provided  for  shelter,  and  the  implements  of  life  ?  Prepare  an  analysis  of  Section  I. 

II.  What  minerals  characterize  the  different  regions  of  North  America?  What  is  the  nature 
and  extent  of  the  mineral  wealth  of  Europe  ?  Of  Asia  ?  Of  South  America  ?  Of  Africa  ?  Of 
Australia  ?  In  what  condition  do  the  several  important  metals  occur  in  nature  ?  (114. )  Which 
metals  were  earliest  brought  into  use  ?  What  reason  can  you  suggest  for  the  use  of  copper 
earlier  than  iron?  What  especial  importance  was  attached  to  the  distribution  of  the  metals, 
and  of  some  other  articles,  in  remote  antiquity  ?     Prepare  an  analysis  of  Section  II. 

The  Human  Family.  I. 

To  what  extent  is  the  human  family  dispersed  over  the  globe?    In  what  zone  are  the  larger 


122 


REVIEW. 


proportion  of  mankind?  On  what  basis  is  mankind  divided  into  races?  How  many  are  the 
geographical  races,  and  where  are  they  located?  (115.)  What  are  the  characteristics  of  each 
of  the  primary  races?  What  are  the  relations  of  the  secondary  races  to  the  primary?  What 
are  the  characteristics  of  the  typical,  or  ideal,  man?  Where  are  these  ideal  proportions  real- 
ized? (110.)  How  are  deviations  from  these  proportions  to  be  regarded?  How  does  the  type 
vary  in  departing  from  the  geographical  centre  of  the  races  ?  Describe  the  successive  modifi- 
cations towards  the  southwest;  towards  the  southeast;  towards  the  northeast;  southward 
through  America.     Prepare  an  analysis  of  Section  I. 

II.  (118.)  What  are  the  evidences  of  unity  in  the  human  family?  What  is  the  law  of  the 
perfection  of  type  in  man?  What  and  where  are  the  three  great  branches  of  the  White  race? 
What  has  been  the  function  of  each  in  the  gradual  development  of  civilization  ?  What  is  the 
condition  of  the  Yellow  race  in  regard  to  culture?  Of  the  Negro?  Of  the  secondary  races? 
What  remains  of  ancient  civilization  has  America?    Prepare  an  analysis  of  Section  II. 

Conclusion.  I. 

What  is  the  importance,  and  what  the  character  of  the  three  great  terrestrial  contrasts  ? 

Note.  —  In  Part  V.  the  Analyses  have  been  omitted  In  order  to  give  the  pupil  an  opportunity  to  analyse 
to  him.     It  would  be  well  t*  require  him  to  make  a.  tabular  analysis  of  each  section  as  he  proceeds  with  the 


What  are  the  characteristics  of  the  oceanic  world?  Of  the  continental?  (119.)  What  region 
of  the  continents  appears  most  favorable  to  development?  What  are  its  advantages?  Give 
examples  of  its  superiority.  What  are  the  contrasting  characteristics  of  the  New  World  and 
the  Old?  Of  the  northern  and  the  southern  continents?  What  especial  character  has  each  of 
the  continents  of  nature?     Prepare  an  analysis  of  Section  I. 

II.  What  are  the  especial  characteristics  of  Asia?  What  has  been  its  function  in  the  develop- 
ment of  mankind?  How  is  Asia  adapted  for  that  particular  phase  of  human  progress1'  What 
and  where  were  the  great  centres  of  primitive  civilization?  (120.)  What  are  the  especial 
characteristics  of  Europe  ?  Where  were  the  earliest  seats  of  European  civilization  ?  Why  in 
those  regions  ?  What  is  the  historical  function  of  Europe  ?  Examples.  (121.)  How  is  Amer- 
ica characterized  in  structure?  In  climate?  What  is  the  nature  and  extent  of  these  diversi- 
ties? Describe  the  most  characteristic  portions  of  this  continent.  What  appears  to  be  the 
providential  plan  for  America?  What  evident  fitness  does  she  show  for  this  work?  What 
conclusion  is  enforced  by  this  study  of  the  continents  of  history?  Prepare  an  analysis  of 
Section  II. 

the  several  sections  — an  exercise  for  which  he  should  now  be  fully  prepared,  and  whioh  will  be  of  advantage 
study. 


GENERAL    REVIEW. 


PART  I. 

(Page  I.)  What  are  the  geographical  elements  of  the  globe?  (5.)  What  advantages  has  the 
Earth  over  the  other  planets  in  its  astronomical  conditions?  (6.)  What  is  the  specific  gravity 
of  the  globe?    (7.)  What  is  the  relation  of  longitude  to  time? 

(8.)  What  is  magnetic  declination,  and  how  is  it  caused?  (9.)  What  is  magnetic  inclination? 
(10.)  Explain  the  formation  of  the  geysers.  (11.)  Explain  the  formation  of  artesian  wells. 
(12.)  What  is  the  average  rate  of  increase  of  heat  towards  the  interior  of  the  Earth?  Explain 
the  formation  of  volcanic  cones. 

(15.)  What  is  the  general  distribution  of  volcanoes  upon  the  globe?  (16.)  What  is  the  pri- 
mary source  of  volcanic  activity?  Describe  the  different  kinds  of  earthquake  motion.  (17.) 
What  is  the  condition  of  scientific  knowledge  in  regard  to  the  cause  of  earthquakes? 

PART  II. 

(21.)  What  grand  contrasts  are  observed  in  the  position  and  grouping  of  the  land  masses? 

(23.)  How  do  the  several  continents  compare  in  the  amount  of  articulation  of  their  coasts? 
What  (page 22)  is  the  importance  of  these  irregularities  of  outline?  (24.)  Define  the  different 
classes  of  relief  forms.  (25.)  How  do  the  different  classes  of  plains  varv  in  productiveness? 
(26.)  What  »  the  importance  of  plateaus  in  the  continental  structures?  What  is  the  nature  of 
the  soil  in  most  great  plateaus?  Examples.  How  are  mountain  chains  formed?  (27.)  What 
is  the  origin  and  classification  of  valleys  among  mountains?  Describe  the  formation  of  val- 
leys in  plains  and  plateaus.     Examples*. 

(30.)  What  common  features  are  apparent  in  all  the  continental  structures?  How  are  the 
general  figure,  and  the  individual  contours  of  a  continent  determined?  (31.)  How  do  the  two 
continents  of  the  New  World  compare  in  structure?  (32.)  What  differences  between  the  two 
highlands  of  South  America  and  those  of  North  America?  What  differences  in  the  central 
regions  of  the  two  continents  ? 

(33. )  What  are  the  common  features  of  structure  in  Asia  and  Europe  ?  What  are  the  especial 
characteristics  of  Asia?  (35.)  What  are  the  characteristics  of  the  structure  of  Europe?  (36.) 
What  peculiarity  of  structure  in  its  central  region  ?  Describe  the  structure  and  surroundings  of 
low  Europe.  (38.)  How  does  the  structure  of  Europe  differ  from  that  of  Asia?  Describe  the 
structure  of  Africa  as  a  whole.  (39.)  How  does  Australia  resemble,  and  how  differ  from, 
Africa  in  structure? 

(40.)  Repeat  the  first  four  general  laws  of  relief.  How  is  the  fourth  expressed  in  the  struc- 
ture of  the  several  continents  I  (42.)  Repeat  the  remaining  four  laws.  JVhat  is  the  dominant 
form  of  relief  of  the  several  continents?  Explain  the  formation  of  the  continental  reliefs. 
(43.)  What  is  the  distinctive  character  of  the  continental  islands?  Of  the  oceanic  islands? 
Describe  the  formation  of  the  coral  reefs  and  islands.  (45.)  What  is  the  comparative  value  of 
the  coral  islands  ? 

PART  III. 

(48.)  Explain  the  formation  of  intermittent  springs.  Describe  the  erosive  action  of  rivers  in 
different  parts  of  their  course.  (50.)  Explain  the  formation  of  deltas.  (51.)  Explain  the  ex- 
istence of  salt  lakes.     Examples. 

(52. )  Describe  the  geographical  distribution  of  lakes  ?  Describe  and  explain  the  general  plan 
of  drainage  of  North  America.  (54.)  Trace  and  explain  the  correspondences  between  the  river 
systems  of  Soulh  America  and  those  of  North  America.  (55.)  Describe  the  general  plan  of 
drainage  of  Eastern  Asia.    What  are  the  main  hydrographical  centres  of  Europe? 

157.)  Describe  the  general  plan  of  drainage  in  Africa.  Describe  the  Nile  system  and  explain 
its  inundations.  What  are  the  peculiarities  of  the  drainage  of  Australia?  What  general  bet 
is  brought  to  light  by  a  study  of  the  distribution  of  river  systems? 

(58.)  How  does  the  surface  temperature  of  the  sea  vary?  (60.)  What  are  the  greatest 
depths  of  the  ocean?  What  are  the  comparative  depths  of  the  inland  and  border  seas?  (61.) 
Describe  the  production  of  the  tidal  waves.  (62. )  Explain  the  spring  tides  and  neap  tides. 
(64.)  What  is  the  average  height  of  the  tide  on  the  eastern  coast  of  North  America  ?  (65. )  De- 
scribe the  general  circulation  of  the  sea,  with  the  cause.  What  are  the  directions  of  the  polar 
and  return  currents?  How  is  this  direction  explained?  (67.)  Describe  the  climatic  effects  of 
the  marine  currents. 

PART    IV. 

(69.)  How  is  the  pressure  of  the  atmosphere  measured?  What  is  the  effect  of  elevation  on 
the  density  of  the  air  ?  At  what  elevation  is  the  pressure  reduced  one  half  ?  (70. )  On  what  do 
the  fundamental  laws  of  climate  depend  ?  State  and  explain  the  general  law  of  the  distribu- 
tion of  temperature  upon  the  globe.  Explain  the  varying  length  of  day  and  night,  and  the 
change  of  temperature  in  different  seasons. 

(72.)  In  what  do  the  general  deviations  from  astronomical  climates  consist,  and  how  are  they 
caused?     To  what  are  local  deviations  due,  and  in  what  do  they  consist?     (73.)  Explain  the 


extreme  contrasts  in  temperature,  on  the  opposite  coasts  of  the  North  Atlantic.  How  does  the 
greater  or  less  area  of  a  land  mass  affect  its  temperature  iu  the  different  zones?  What  are  the 
characteristics  of  the  continental  climates?  Of  the  oceanic?  Explain  the  cause  of  this  dif- 
ference. 

(76.)  Describe  and  explain  the  general  circulation  of  the  atmosphere.  (77.)  Name  the  sev- 
eral wind  zones,  and  give  their  positions?  What  is  the  cause  (page  76)  of  the  trade  winds, 
and  to  what  is  their  direction  due  I  What  is  the  position  and  cause  of  the  equatorial  calms? 
(78. )  Explain  the  monsoons  of  the  Indian  ocean.  Explain  the  diurnal  land  and  sea  breezes. 
(79.)  What  are  the  prevailing  winds  of  the  temperate  zones?  What  is  the  direction  of  the 
return-trades,  and  what  gives  them  (page  76)  this  direction?  Whence  do  the  polar  winds 
start?  What  is  their  direction  in  Eastern  Asia  and  North  America?  Why?  Why  are  the 
polar  winds  less  powerful  in  summer  than  in  winter?  What  causes  the  frequent  storms  of 
spring  and  autumn  ?     What  causes  a  late  spring  or  autumn  ?     An  early  spring  or  autumn? 

(82.)  What  is  the  character  of  the  storms  known  as  hurricanes?  (83.)  What  are  water- 
spouts? (84.)  On  what  does  the  capacity  of  the  air  for  the  absorption  of  vapor  depend  ?  (85. ) 
How  do  mountains  affect  the  condensation  of  vapors?  Examples.  How  do  tin;  nature  and 
covering  of  the  soil  affect  the  condensation  of  vapor?  (88.)  State  the  general  law  of  the  dis- 
tribution of  rain  on  the  globe.     The  law  of  distribution  of  cloudiness  and  vapor. 

(89.)  State  the  general  cause,  and  the  time,  of  rain  in  the  different  zones.  Describe  and  ex- 
plain the  rainfall  in  the  belt  of  calms;  in  the  belt  of  trades.  (90.)  What  is  the  comparative 
amount  of  rain  in  the  subtropical  zones?  Why  is  this?  What  is  the  cause  of  the  winter  rains, 
and  where  do  they  occur ?  What  is  the  comparative  amount  of  moisture  in  South  America? 
Why  is  this  ?  What  is  the  especial  character  of  Africa  in  regard  to  rain  ?  Why  is  Northern 
Africa  so  dry  ?  What  is  the  comparative  amount  of  rain  in  Australia  as  a  whole  ?  How  do 
you  explain  the  abundant  rainfall  in  the  eastern  half  of  North  America?  Why  are  the  high 
western  plains  and  plateaus  so  dry  ?     What  is  the  comparative  amount  of  rain  in  Europe  ? 

(92.)  How  does  Asia  compare  with  the  other  continents  in  the  amount  of  rain  it  receives? 
Why  is  this?  In  what  latitudes  does  snow  fall  at  the  level  of  the  sea?  (93.)  On  what  imm 
the  height  of  the  snow  line  depend?  Where  is  it  greatest?  (94.)  Describe  the  formation  of  a 
glacier.     (95. )  What  are  icebergs  ?     What  is  the  supposed  cause  of  the  auroras  ? 

PART  V. 

(97. )  How  is  the  system  of  life  in  nature  represented  ?  What  is  the  function  of  the  plant 
in  the  economy  of  nature  ?  What  are  the  climatic  conditions  of  the  development  of  vegetable 
life?  What  is  the  characteristic  vegetation  of  each  of  the  several  zones?  (102.)  How  does 
vegetation  vary  at  different  altitudes?  Why  is  this?  Describe  the  vegetation  of  the  Andes  in 
the  several  vertical  zones.  What  is  the  general  character  of  the  vegetable  world  in  Africa? 
Why?  (104.)  What  are  the  especial  characteristics  of  the  vegetable  world  in  South  America? 
Why  is  this?  What  useful  plants  are  indigenous  in  tropical  America ?  (105.)  What  is  the 
general  character  of  the  Australian  flora? 

(106.)  What  is  the  general  law  of  the  development  of  life  in  nature?  Name  the  character- 
istic species  of  animals  of  tropical  regions.  (107.)  What  are  the  characteristic  animals  of  the 
temperate  zone?  What  are  the  characteristic  animals  of  the  cold  zones?  (108.)  What  are  the 
'  especial  characteristics  of  the  animal  world  in  North  America?  What  orders  of  animals  char- 
I  acterize  Asia ?  (109.)  What  is  the  general  character  of  the  animal  world  in  Africa?  What  are 
the  characteristics  of  the  South  American  fauna?  What  divisions  of  the  animal  kingdom  espe-  ; 
cially  distinguish  this  continent?     Describe  the  fauna  of  Australia. 

(111.)  How  does  the  sustenance  of  man  vary  in  the  different  zones?     In  what  zone  are  most    i 
of  the  food  plants  of  civilized  nations  indigenous?     From  what  zone  are  most^f  the  luxuries 
derived?   (112.)  What  continents  are  especially  characterized  by  the  abundance  of  the  precious 
metals?    Which  are  distinguished  by  the  abundance  and  variety  of  the  useful  metals?    Which 
has  the  most  extensive  coal  fields  ?     What  metals  were  most  anciently  in  use  ?    What  was  the    I 
commercial  importance  of  the  metals  in  antiquity  ? 

(114.)  What  is  the  location  and  number  of  the  geographical  races?  State  the  especial  charac- 
teristics of  each  race?  (115.)  Which  approaches  most  nearly  to  the  typical  man?  Where  is 
this  normal  race  found  in  its  highest  physical  perfection?  (116.)  What  is  the  general  law  of 
the  variation  of  types  in  man  ?  Which  race  occupies  the  highest  grade  in  intellectual  culture  S 
and  social  condition  ?  What  are  the  three  great  families  of  the  white  race  ?  What  has  been 
the  especial  work  of  each  in  the  progress  of  civilization?  What  is  the  condition  of  the  yellow 
race,  and  their  relation  to  the  general  progress  of  mankind? 

(118.)  What  are  the  three  great  terrestrial  contrasts?  What  contrasting  characters  are  dis- 
played by  the  life  in  the  continental  and  the  oceanic  world  ?  What  is  the  region  apparently 
most  favorable  to  all  development?  What  are  its  especial  advantages  for  the  development  of 
life  in  nature?  For  human  progress?  What  are  the  contrasting  characteristics  of  the  eastern 
and  western  worlds?  Of  the  northern  and  southern  worlds?  What  are  the  especial  functions 
of  the  several  southern  continents?  (119.)  What  has  been  the  historic  function  of  Asia,  and 
how  was  it  adapted  for  this  work?  What  has  been  the  function  of  Europe,  and  how  was  it 
fitted  for  its  work?  What  appears  to  be  the  providential  design  in  regard  to  America?  What 
characteristics  indicate  such  a  work  for  our  continent  ?  I 


PRONUNCIATION    OF    NAMES    EMPLOYED   IN    THE    TEXT. 


Explanation,  a,  e,  T,  6,  u,  as  ia  mate,  mgte,  mite,  mote,  mute  ;  a,  e,  i,  6,  u,  a  trifle  shorter  than  a,  etc. ;  a,  e,  I,  6,  tt,  as  in  mat,  m5t,  It,  n5t,  Up  ;  a,  8,  i,  o,  fl,  aa  in  care,  there,  firm,  f&r,  fdrl ;  a,  as  in  far  ;  ft, 
as  in  fall  ;  a,  as  in  last ;  p.,  as  in  dp, ;  6,  as  in  dune  ;  y,  as  in  rude ;  y,  as  in  push ;  8,  as  in  term ;  a,  5,  o,  as  in  fragrance,  Salem,  Hudson. 

g,  as  in  go  ;  n,  as  in  canon  (can 'yon) ;  N,  silent,  indicating  that  the  preceding  vowel  has  a  nasal  utterance,  as  though  pronounced  with  the  nostrils  closed  (as  in  Toulon,  tu-lOx,  where  the  6  is  the  last  sound  heard 
in  the  word) ;  u,  as  in  his ;  «fa,  as  in  e&air.     All  consonants  not  marked  have  the  same  sound  as  in  corresponding  positions  in  ordinary  English  words. 


Abyssinia,  ab-Is-In'I-a 
Aconcagua,  a-k5n-ka/gwa 
Adriatic,  ttd-rf-at/Tk 
Afghanistan,  af-gau1  Is-tau' 
Amos,  a/i-nos 
Aleutian,  a-lu'shi-au 
Aleuts,  li-luts' 
Algonquin,  al-gou'kwln 
Altai,  al-tl' 
Aluta,  a-lu/ta 
amargoza,  ain-ar-go'zs 
Amargura,  ani-ar-gu/rii 
Amazon,  im/a-zyn 
Amoo,  a/moo 
Amoor,  a-niooV 
Andaman,  aVda-niau' 
Antilles,  an-tel  or  an-tll'lSs 
Apache,  a-pa'efee 
Apennines,  ilpv£n-nlus/ 
Appalachian,  ap*  pa-la/ eke-au 
Apurimac,  a-poo^re-mak' 
Arab,  ar'ab 
Arafura,  a-ra-fu'ra 
Aral,  ar'al 
Ararat,  ilr'a-rat 
Araucanians,  a-ro-ka'ue-^ns 
Araucaria,  a-ru-ka/re-a 
Ardennes,  ar-den' 
Arequipa,  avra-ke'pa 
Arnhem,  an/hem 
Artois,  ar-tois'  or  ar-twa' 
Ashantee,  a-shun'te 
Atbara,  iit-bii'ra 
Athabasca,  ath-a-bas'ka 
Athabascans,  ath-a-baVkaua 
Aujlla,    Od-je'la 
Azores,  a-zors' 

Star,  ba^fir 

Bahama,  ba-ha/ma 

Baikal,  bl'kal 

Balaton,  ba/lij-toft 

Balkan,  bal-kan' 

Balkhash,  biil-kasb/ 

Bangweolo,  bang^a-o^lo 

Barnaul,  barn-owl' 

Bayonne,  ba-ygn' 

Bayou,  bl'yoo 

Behring,  ber'Ing 

Bengal,  ben-gal' 

Benue,  ben'u-il* 

Bergen,  beVgen 

Bermudas,  b&r-niu-daj 

Bhootan  or  Bhotan,  boo-tiin/ 

Bogota,  bo*go-ta/ 

Bolabola,  boMa-bo'la 

Bonin,  bo-nen' 

Boorlos,  booVlos 

Boothia,  b<x/thea 

Borneo,  bOr'ne-6 

Botocudos,.bovto-cuMos 

Bourbon,  boor'bon 

Brahmapootra,  bravnia-poo/tra 

Brazos,  bra'zOs 

Hretagne,  hre-tan' 

Bug,  boog 

Cabool,  ka-booV 
Candahar,  kan-da-har' 
OaSon,  kan'yon 
Cashmere,  kash-mfir' 
Casiquiare,  kavs5-kG-a'ra 
Catamarca,  ka-ta-inar'ka 
Caucasians,  k^-kas/I-aos 
Caucasus,  ka/ka-sQs 
<   1  very,  kii-va/rl 
Cayambe,  kT-iun'ba 
Celebes,  sSKe-bes 
Celtic,  sfilfik 
Ce venues,  sa-vSn' 
Ceylon,  se'Ion 
Chagos,  ekii'gos 
Hianialare,  «ham-a-UVre 
Charollais,  ihjfrolHft' 
Charybdis,  kar-It/dTs 
Chwbooiy,  shr-r-boorg' 
Cherraponjee,  ekgr^ra-pp.u'jt- 


Chili,  diiKe 
Chilian,  efell'i-an 
Chimborazo,  chhn-bo-ra'zo 
Chippeways,  ehtp'pii-was/ 
Coimbra,  ko-em'bra 
Colorado,  k6T6-ra'd6 
Cossyah,  kos'se-a 
Costa  Rica,  koVta-re'ka 
COte  d'Or,  kot'dGV 
Cotopaxi,  koUo-pax'e 
Crimea,  krlm-e'a 
Cuzco,  kus/ko 

Dakota,  da-kr/ta 
Dapsang,  dap-sang7 
Deccan,  dek'an 
Dhawalagiri,    da-w61va-ger're 
Diamantina,  de-a-man-te'na 
Dnieper,  ne'per 
Dravida,  dra-ve'da 
Dyak,  dl^ak 

Ecuador,  ek-wa-dor7 

Eifel,  I'fel 

Elburz  or  Elbourz,  el-burz' 

EI  Gran  Chaco,  61-grau-eba'ko 

Ellice,  ells 

Erebus,  eVe-btls 

Erz,  erts 

Esquimaux,  eVke-uios 

Euphrates,  Q-fra'tes 

Eyre,  ar 

Ferdinandia,  ferMe-nau'dl-a 
Fichtel.fish'tel 
Forez,  fo-ra/ 
Formosa,  fOr-mo'sji 
Fuegians,  fu-e'je-aus 
Fuego,  fu-a/go 

Gairdner,  gardener 
Galapagos,  gii-la-pa'gos 
Gallas,  gaVfis 
Garonne,  ga-rOn' 
Gavaruie,  ga-vaVue 
Geyser,  gi'ser 
Ghauts,  gate 
Gobi,  go'be 
Guaranls,  gwa-raVnSs 
Guiana,  ge-a/na 

Hamoon,  ha-moon' 
Hardt,  hart 

Harmattan,  har-mat'tau 
Harz,  harts 
Hawaian,  ha-wl'an 
Hawaii  or  Hawai,  ha-wl'e 
Hawash,  ha/wash 
Hayti,  ha'te 
Haytian,  ha/te-au 
Heath,  hSth 
Hellenic,  hel-6n'ik 
Helmund,  hel'mQnd 
Henuake,  hfin^u-a'ka 
Hercynian,  hSr-sTu'e-an 
Hielmar,  hy-6Kmar 
Himalaya,  hTm-a-la/ya 
Hindoo  Kocsh^hin'doo  koCsh' 
Hoangho,  ho-ang'bo^ 
Hogoleu,  ho'go-lii 

Idaho,  Kda-ho 
Itjamin,  Tl-ya'mTn 
Illimani,  el-yema'ne 
Irasu,  C-raAu. 
Irawaddy,  Tr-a-wod'e 
Ismailia,  Ts-ma/t'l-ya 

Jan  Mayen,  yan  inT'$u 
Jebel-Kibrit,  j6b-Cl-kIbMt 
Jolof,  jSKpf 
Jorullo,  ho-rool'yS 

Kaffa,  kaFfa 
Kaffre,  kaf-fer 
Kalmuks,  kaKmuks 
Kamchadale,  k.-lm'eha-dal4 


Kamchatka,  kam-eb.at/ka 
Kamsin,  kam'sln 
Karakorur^,  kaVa-ku'rOm 
Keelfoss,  keKfos 
Kenai,  ke-na'e 
Kenia,  ke'ne-a 
Kermadec,  kSr^ma-dek7 
Khassia,  kas'se-a 
Khingan,  kln-gan' 
Kilauea,  keMo'5-a 
Kilima  Njaro,  kll^-mau^a-ro' 
Kirghiz,  kSi/ges 
Kolushians,  ko-Iij'she-^ng 
Koriaks,  ko're-aks 
Kossogol,  koe-6-g5K 
Kuenlun,  kwBn-loon' 
Kurdistan,  koord-Is-tau/ 
Kurile,  koo'rel 
Kuro  Sivo,  kjj'ro  s&'vO 

Uiceadive,  Ulk-a-dtv' 
Lachlan,  lak'lan 
Ladoga,  lad'o-ga  or  la-dc/ga 
Landes,  lasdz 
iAngres,  laNg'r 
La  Paz,  la  pSz 
Lapponic,  lap'po-nik 
Iceman,  lavmaN/ 
Ijtua,  lu-na/  or  le'na 
Levees,  16v-es/ 
Limpopo,  Hm-po^po 
Llano,  Tya'no 
Lofoden,  lo-fc/den 
Loire,  l'war' 
Lucerne,  loo-sern' 
Lugano,  lU-ga/nd 

Miu.-oti.  ma^s6N/ 

Madeira,  nia-de'rjj 

Maelar,  ma'lar 

Maelstrom,  miiPstrtlni 

Magdalena,  mag-da-le-'na 

Mageroe,  ma/ge-ro 

Maggiore,  mad-jo'Va 

Mahabuleshwur,  ma^ha-bl6sh-war' 

Maldive,  mai-dlv' 

Malgache,  maPgash' 

Malpays,  mai-pa'e 

Manchoo,  mau'efeoo 

Manchuria,  man-clioo're-a 

Mandingo,  man-dmg'go 

Mantiqueira,  manHe-ka/ra 

Maori,  ma'o-re 

Maracaybo,  or  Maracaibo,uia*ra-ki/bo 

Maranon,  ma-ran-you7 

Maravaca,  maY.i-vii'ka 

Mareotis,  ma-ra-o'tes 

Margeride,  mar-zhf-red' 

Marianne,  miPre-an' 

Maros,  mar-osh' 

Marquesas,  mar-ka'sas 

Mauna  Kea,  ma-na  kS'a 

Mauna  Loa,  mji-na  lo^a 

Maures,  mor 

Mauritius,  ma-rish'e-lls 

Mekong,  mil-kong' 

Melanesia,  mePa-ncAshl-a 

Melrir,  mt-Kriir 

Menzaleh,  men-za'li: 

Merapi,  ma-ra'pi; 

Me  use,  muz 

Micronesia,  mlc'ro-nC'shl-n 

Moero,  mo-a'ro 

Molucca,  mo-lflk'a 

Monte  Somma,  mon  t«"  >mn'uiu 

Muisca,  mu-Is'ka 

Mur,  mur 

Muxinga,  mHx-Tng'ga 

Narcondam,  nar-con^dam 
Natron,  na'tron 
Natupe,  na-ti/pa 
Nevada,  na-va/da 
Nevado,  na-va'do 
Newfoundland,  nu/ftlud-land, 
Ngai,  n'ga/e 
Ngami,  n'ga'me 


Nicaragua,  nlc-a-rj/gwa 

Nicobar,  ulc'o-bar^ 

Nieuweveld,  nyuw'velt 

Niger,  BfQgV 

N'ovaiaZemlia,  no-vi'U  zcui'le-a 

\yanza,  ni-au'za 

Nyassa,  nT-as/sa 

Obi,  o'be 
Ofen,  o-'fgn 
Ohiwao,  o-he-wa'o 
Okhotsk,  o-kotsk' 
Onega,  o-ue'ga 
Orizaba,  o-re-za/ba 

Pamir,  pa-iner' 

Pampa,  pam'pa 

Panama,  pan-a-ma/ 

Papuan,  pap'oo-an 

Paraguay,  paVa-gwfi/ 

Parana,  pavra-na/ 

Paumotu,  pow^mo^tu 

Penas,  p&n'yas 

Persian,  p£r'sh6-an 

Peschawer,  pfish-ow^r 

Petchora,  peeb'o-ra 

Philippine,  fiKip-in 

Pic  Anethou,  pek^  a-ua'too 

Pico  de  Teyde,  pe'ko  de  ti'de 

Pilcomayo,  pIPko-mi'o 

Pitcairn,  pit-karn/ 

Polynesian,  pfin-nu'shi-an 

Popocatepetl,  po-po  katxa-p6tl/ 

Porto  Rico,  por'to  rcrk6 

Pruth,  prooth 

Punta  Parina,  pooi/ta  pa-r^'na 

Purus,  poo'roos 

Pyrenees,  pir'e-ues 

Quathlamba,  kwat-liim'ba 
Quechua,  kwa-ebU'a 
Quito,  ke'to 

Radack,  ra'dak 
Rainier,  ra/ner 
Ralick,  ra/llk 
Rauh, rau 
Reisen,  re-sgn 
Reykjavik,  r^kT-a-vIk* 
Rhenish,  ran'Ish 
Rio  Grande,  ri'6  grand 
Rio  Janeiro,  n'S  jan-e'ro 
Rilo  Dagh,  re'lo  dah' 
Roumania,  roo-ma'ne-a 

Samarang,  sam-a-rang' 

Samiel,  sa'ml-Cl 

Samoa,  sa-mo'a 

Samoiedes,  sa-moKeds 

Sampu,  sam'poo 

Santorini,  san-to-rt/ne 

Sadne,  son 

Sarmiento,  sar-nid-fin'to 

Saskatchewan,  sas-kaek/e-wan'' 

Scandinavia,  skanMI-na'vT-a 

Seathwaite,  seth'wfit 

Seine,  san 

Sereth,  ser-eV 

Seychelles,  sa-shfiK 

Shamo,  sha'mo 

Shasta,  shas'ta 

Shoshonee,  sho-sho^ne 

Sidrj,sld'ra 

Sierra,  se-eVrii 

Siestan,  pOe^t&a 

Sikhota  Alin,  fl'-kc/t'&  a/len 

Simoon,  se  moon' 

Sioux,  so6s 

Sir  Daria,  ser  da-'re-a 

Sir-i-kul,  ser'e-kai' 

Siwa  or  Si wah,  sS'vu 

Sneeuw,  snC-oov' 

Socotora,  so-ko'trii 

Somali,  so-uia'le 

Sorata,  sd-rii^ta 

Staubbach,  staub'bak 


Soudan ,  soo-dau' 

Steppes,  steps 

Stromboli,  strOm-bo'le 

Suabo-Frauconian,  swr/bo-frau^kyne-an 

Suaheli,  suva-ha^l« 

Sudetic,  su-deVlk 

Sulltelma,    sU-li-tel'ma 

Suliman,  su-le-man' 

Sunda,  sun'da 

Tahiti,  ta-he'te 

Taiara,  tl-a'ra 

Tanganyika,  tan'gan-ye^kft 

Tanta,  tai/ta 

Tapajos,  ta-pa/zhos 

Tarawan,  ta^ra-wan' 

Tarim    ta/rem 

Ta  Siue  Shan,  ta  sevwa/shiLu 

Tchad,  ebad 

Tchukchees,  eJiook'^bes 

Tebu,  ta/bu 

Tengri  Nor,  tfin^gre  nor 

Tenuyan,  ten-we'an 

Terai,  ta-ra'e 

Tequendama,  ta*kw6n-da'ma 

Teutoburg,  toKto-boorg 

Theiss,  tis 

Thian  Shan,  te^an'  shau 

Thibet,  tlb-et  or  tl-b6t' 

Thibetan,  tlb-et'an 

Thuringian,  thjj-rln'je-an 

Titicaca,  te-te-ka'ka 

Tocantins,  to^kan-tenz7 

Tolima,  to-le'mii 

Tolmezzo,  toi-mfit'zo 

Transylvania,  tran^ll-va'ul-a 

Tristan  da  Cuiiha,  trls'tan-da-kun'ya 

Tsien-tang,  tse-gn'taug 

Tuareg,  too-a-rgg' 

Tubuai,  tu-bu'I 

Tufoa,  tu-fo'il 

Tundra,  toon'dra 

Tungusian,  toon-gu'zhl-ftD 

Tupis,  too-pes/ 

Tupungato,  tu-pHDg-ga'tS 

Turooman,  toorvko-man, 

Turkestan,  toor,kes-tan/ 

Tzana,  tza/nii 

Ucayali,  oo^ki-fi'le 
Ugrian,  oVgre-au 

Unalashka,  oT/nii-la-li'kii 
Ural,  yu'ral 
Uruguay,  yoVroo-gwa 
Urumia,  oovroo-me/a 
Utah,  yoVta 

Valdai,  vaKdi 
Valdivia,  vaTde/ve-a 
Vermejo,  vfir-mS/ho 
Vesuvius,  ve-soo^ve-tis 
Vindhya,  vlud'ya 
Vistula,  vls'too-la 
Volga,  vdl'ga 
Vosges,  vozh 

Wahsatch,  wa-saek' 
Walachia,  wU-la'ke-a 
Warasdin,  wa%r^s-den' 
Wener,  wa'ngr 
Weser,  we-zgr 
Wetter,  wgt'er 

Xingu,  sheu-goo' 

Yablonoi,  ya-blo-noi' 

Yakutsk,  ya-ko3ts/k 

Yangtse  Kiang,  jangHse  kt-aug' 

Yanteles,  yan-ta'16s 

Yapura,  ya-pu'rii 

Yenisei,  yen-e-saf 

Yosemite,  yS-sBm'i-tP 

Zambesi,  zam-ba'ze 
Zermatt,  z6r-maV 


124 


TABLES    OF  TEMPERATURE   AND   RAINFALL. 


TABLE  OF  MEAN  TEMPERATURE  AND  RAINFALL  IN  THE  UNITED  STATES. 


NAMES   OF  PLACES. 


EAST  OF  MISSISSIPPI    RIVER. 


Michipicoten,  Lake  Superior 

Fort  Kent,  Me 

Mackinac,  Mich 

Eastport,  Me 

Fort  Snelling,  near  Bt.  Paul,  Min. . 
Potsdam,  St.  Lawrence  Co.,  N.  Y. . 

Fort  Howard,  Wis 

Burlington ,  Vt 

Sackett's  Harbor,  N.  Y 

Hanover,  Dartmouth  College,  N.  H. 

Portland,  Me 

Concord,  N.  H 

Rochester,  N.  Y 

Prairie  du  Chien,  Wis 

Portsmouth,  N.  H 

Milwaukee,  Wis 

Buffalo,  N.  Y 

Albany,  N. Y 

Amherst  College,  Mass 

Boston,  Mass 

Detroit,  Mich 

Chicago,  111 

Providence,  R.  I 

Cleveland, 0 

Fort  Armstrong,  Rock  Island,  111. . 

West  Point,  N.  Y 

New  Haven,  Conn 

Nantucket,  Mass 

Logansport,  Ind 

New  York,  N.  Y... 

Pittsburg,  Pa 

Philadelphia,  Oirard  College,  Pa.. . 

Marietta,  0 

Baltimore,  Md 

Cincinnati,  0 

Washington,  D.  C 

Fort  Washington,  Md 

Louisville,  Ky 

Richmond,  Va 

Fortress  Monroe,  Va 

Nashville,  Tenn 

Knoxville,  Tenn 

Chapel  Hill,  N.  C 

Memphis,  Tenn 

Huntsville,  Ala 

Columbia,  S.  C 

Smithville,  Fort  Johnston,  N.  C. . . 

Augusta,  Ga 

Charleston,  S.  0 

Savannah ,  Ga 

Natchez,  Miss 

Mobile,  Ala 

Baton  Rouge,  La 

Pensacola,  Fla 

New  Orleans,  La 

St.  Augustine,  Fla 

Cedar  Keys,  Fla 

Tampa  Bay,  Fla 

Fort  Dallas,  Fla 

Key  West,  Fla 

WEST  OF  MISSISSIPPI   RIVER. 

Point  Barrow,  Alaska 

Fort  Yukon,  Alaska 

Sitka,  Alaska 

Pembiua,  Dak 

Fort  Union,  Dak 

Fort  Benton,  Mont 

Steilacoom,  W.  T 

Astoria,  Or 

Fort  Pierre,  Dak 

Fort  Orford,  Or 

Dubuque,  Iowa 

Fort  Dodge  (Clarke),  Iowa 

F'ort  Laramie,  Wyo 

Des  Moines,  Iowa 

Council  Bluffs,  Iowa 

Salt  Lake  City,  Utah 

Fort  Kearney,  Neb 

Fort  Heading,  Cal 

Denver,  Col 

Fort  Loavenworth,  Kan 

Fort  KUey,  Kan 

St.  Lvuis,  Mo 

Sacramento,  Cal 

San  Francisco,  Cal 

Fort  Atkinson,  Kan 

Fort  Scott.  Kan 

Fort  Massachusetts,  Col 

Fort  MBcr,  Cal 

Monterey,  Cal 

8antaFe,  N.  M 

Little  Rock,  Ark 

Fort  Washita.  Ind.  T 

Los  Angeles,  Cal 

Fort  Belknap,  Tex 

Fort  Webster,  N.  M 

Fort  Yuma,  Cal 

San  Diego,  Cal 

Fort  Fillmore,  N.  M 

Fort  Graham,  Tex 

Natchitoches,  La 

Austin,  Texas 

Galveston,  Tex 

Fort  Clark,  Tex 

Brownsville,  Tex 


POSITION   OF   STATIONS. 


North 
Latitude 


47  W 
47  15 
45  51 
44  64 
44  53 
44  40 
44  30 
44  28 
43  55 
43  42 
43  38 
43  12 
43  8 
43  5 
43  5 
43  3 
42  53 
42  39 
42  22 
42  22 
42  20 
41  54 
41  60 
4142 
41  30 
41  24 
41  18 
41  17 
40  4 
40  42 
40  27 
39  58 
39  25 
39  18 
39  6 
38  53 
38  43 
38  10 
37  32 
37 

36  10 
35  59 
35  54 
35  8 
34  43 
33  59 
33  55 
33  28 
32  47 
32  5 
31  34 
30  41 
30  26 
30  24 
29  57 
29  54 
29  7 
28 

25  55 
24  34 


71  21 
66 
57  3 
49 
48 

47  50 
47  10 
46  11 
44  23 
42  44 
42  30 
42  28 
42  12 
41  35 
41  30 
40  46 
40  38 
40  30 
39  44 
39  21 
39  3 
38  37 
38  34 
37  48 
37  47 
37  45 
37  32 
37 

36  36 
35  41 
34  42 
34  14 


32  48 
32  44 
32  42 
32  14 
31  56 
31  33 
30  15 
29  19 
29  17 
25  54 


W.  Long. 

of  Green- 

wich. 

85  6  ' 

68  35 

84  33 

66  59 

93  10 

75  1 

88  6 

73  11 

75  57 

72  17 

70  15 

71  29 

77  51 

91 

70  46 

87  65 

78  65 

73  45 

72  34 

71  4 

83 

87  38 

71  23 

81  36 

90  40 

73  67 

72  55 

70  6 

86  1 

74  1 

79  59 

75  10 

81  31 

76  36 

84  28 

77  1 

77  2 

85  40 

77  27 

76  18 

86  49 

83  54 

79  17 

90 

86  46 

81  2 

78  1 

81  68 

79  56 

81  5 

91  28 

88  2 

91  18 

87  13 

90  4 

81  19 

833 

82  28 

80  20 

8148 

156  17 

147 

135  18 

97 
104 

Alt.  in 

Eng.  feet 

above 

ocean. 


110  36 

122  25 

123  49 
100  12 

124  29 
90  40 

94  3 
104  31 

93  37 

95  48 
112  6 

98  57 
122  5 

104  57 

94  48 

96  35 
90  16 

121  28 

122  27 
100  14 

94  45 

105  23 
119  40 
121  62 

106  2 

92  15 

96  38 
118  12 

98  40 
108  5 
114  36 
117  14 
106  16 

97  26 

93  32 
97  47 

94  47 
100  25 

97  26 


675 

728 
40 


620 

346 

266 

.  530 

20 

374 

500 

642 

50 

591 

600 

75 

267 

60 

562 

591 

150 

625 

628 

167 

50 

30 

625 

23 

850 

133 

630 

30 

582 

40 

60 

450 

172 

8 

533 

1,000 

570 

262 

600 

315 

20 

600 

25 

42 

264 

30 

41 

18 

20 

8 

85 

20 

20 

10 


700 

2,022 

2,663 

300 

60 

1,456 

50 


4,519 

830 

1,260 

4,320 

2,360 

674 

6,000 

896 

1,300 

481 

82 

130 

2,330 

1,000 

8,365 

402 

140 

6,846 

150 

645 

457 

1,600 

6,350 

200 

150 

3,937 

900 

100 

200 

1,000 
50 


TEMPERATURE  IN  DEGREES  FUR 


January 

(Below  ze 

ro-.) 


10.6 
11.1 
19.4 
22.4 
13.7 
18.4 
18.9 
20.6 

15.8 
22.8 
21.2 
26.9 
19.4 
24.9 
25.2 

24.3 

23.7 

27.8 

27 

23.6 

27.5 

22.8 
28.3 

34.9 

15.1 

30.2 

29.1 

32.1 

32.6 

30.9 

30 

28.3 

36.5 

35.8 

33.7 

36.5 

38.2 

30.5 

41.5 

41.7 

42 

49 

46.7 

48.1 

54,4 

52!3 

67.6 

53.5 

53.6 

55.3 

67 

55.6 

61.5 

66.4 

69.6 


-18.5 
-26.6 


21.3 

16.5 

38.7 

48 

19.2 

48.1 

19.8 

19.6 

31 

27.4 

19.4 

27.1 

21.1 

44.2 

82 

28 

27.1 

31.4 

45.3 

49.6 

33.4 

32.9 

19.7 

47 

62.2 

31.4 

40 

42.9 

52.8 

42.3 

40.6 

56.4 

61.9 

44.5 

47.9 

50.6 

46.4 

48.1 

47.2 

60.4 


July. 


57 

62.6 

645 

623 

73.4 

68.4 

71.5 


64.4 
68.2 
67.1 
69.9 
76.3 
67.1 
69.8 

72.1 
71  . 
71.6 
69.7 
70.8 
70.6 

76.5 
73.7 

71 

72.9 

74.8 

73 

74.7 

73.6 

76.2 

74.5 

76.7 

80 

74.6 

77.6 

78.2 

79.6 

74.1 

78.2 

79.9 

76.4 

81.6 
81.9 
80.1 
81.4 
81.8 
83.7 
81.8 
82.3 
82.9 
80.9 
813 
80.7 
82.1 
8&5 


36.1 

65.7 

65.6 

74.4 

,78.6 

73.6 

64.2 

61.6 

76.9 

69.7 

76.2 

76.2 

74.7 

76.5 

76.9 

81.5 

73.6 

82.9 

78 

76.7 

83.7 

78.2 

73.9 

67.9 

79.2 

77.2 

63.5 

90.2 

58.5 

72.6 

80 

80.7 

75 

82.3 

76.1 

92.3 

72.7 

88.4 

83.1 

82.2 

80.7 

88 

81 

84.2 


Year. 


38.2 
37 

40.0 

43 

44.6 

43.6 

44.5 

46 

45.1 

45.2 
44.5 
47 
47.6 
45.8 
46.4 
46.1 
48.2 
46.7 
48.9 
47.2 
46.7 
47.9 
48.9 
50.3 
50.7 
60.8 
50.4 
60.9 
61.7 
50.8 
52.7 
52.6 
63.1 
63.8 
55.1 
•57.8 
64.9 
56.2 
59.9 
68.5 
65.7 
59.7 
60.8 
59.1 
57.1 
65.7 
64 
659 
67.4 
67.1 
70.3 
68.1 
68.7 
69.9 
69.6 
70.6 
71.9 
74.7 
76.4 


7.1 
16.8 
43.2 


48.2 
60.8 
52.2 
61.9 
53.6 
49.4 
47,4 
50.1 
49.7 
49.3 

47.7 

62.1 

48 

52.8 

66.6 

64.5 

69.9 

64.9 

64.6 

64.5 

41.1 

66 

66.3 

50.6 

62.3 

62.2 

62 

64 

54.8 

73.6 

62 

64 

65.7 

66.3 

66.7 

69.4 

67 

73.7 


Annual 
Rainfall 
in  Eng. 
Inches. 


27.81 

36.45 

23.96 

40.09 

25.82 

28,133 

34.62 

34.15 

30.73 

40.32 

43.63 

40.99 

82.56 

35 

29.88 

30.40 

33.84 

40.52 

43.90 

39.40 

30.05 

33 

41.38 

37.61 

38 

47.65 

44.43 

41.10 

37.34 

44.59 

47.68 

35.55 

42.55 

40.84 

44.87 

41.05 

45.02 

48.12 

38.29 

47.04 

52.02 

39.76 

42.71 

45.46 

54.88 

47.17 

46.01 

24.20 

41.92 

48.32 

63.55 

64.42 

60.16 

59.27 

61.05 

48.16 

45.77 

61 

69.04 

36.23 


83 
16 
11 

12.60 
43.98 
86.36 
13.51 
70.59 
33.47 
26.82 
1516 
23.94 
29 

28.85 
25.26 
29.11 
16 

31.74 
23.62 
42.48 
19.59 
23.50 
23 

42.15 
17.06 
18.99 
12.20 
17 
47 

38.04 
13 

28.05 
19.46 
346 
9.16 
8.42 
40.58 
64 

30.50 
42 

22.38 
37 


TABLE  OF  MEAN  TEMPERATURE  AND  RAINFALL  IN  THE  WORLD. 


NAMES  OF  PLACES. 


Hammeifest,  Norway 

Archangel,  Russia 

Reykjavik,  Iceland 

Bergen ,  Norway 

St.  Petersburg,  Russia 

Christiauia,  Norway 

Ekaterinburg,  Russia 

Edinburgh,  Scotland 

Moscow,  Russia 

Bremen,  German  Empire 

Dublin,  Ireland 

Berlin,  Prussia 

Warsaw,  Poland 

London,  England 

Brussels,  Belgium 

Paris,  France 

Vienna,  Austria 

Odessa,  Russia 

Astrakhan,  Russia 

Lyon,  France -. 

Milan,  Lombardy,  Italy 

Bordeaux,  France 

Belgrade,  Turkey 

Florence,  Italy 

Constantinople,  Turkey 

Madrid,  Spain 

Lisbon,  Portugal 

Naples,  Italy > 

Athens,  Greece ^ . 

AFRICA. 

Algiers,  Algeria 

Funchal,  Madeira 

Cairo,  Egypt 

Kuka,  Bornu 

Christiansborg,  Guinea , 

Gondokoro 

Zanzibar 

St.  Helena 

Port  D'Urban,  Natal 

Cape  Town,  Cape  Colony 

ASIA. 

Ust  Yansk,  Siberia 

Yakutsk,  "      

Okhotsk,  "      

Tobolsk,  " 

Barnaul,  M       

Petropaulovski,  Kamchatka 

Irkutsk,  Siberia 

Tiflis 

Peking,  China 

Baghdad,  Asiatic  Turkey 

Nagasaki,  Kiusiu,  Japan  

Jerusalem,  Syria 

Canton,  China 

Calcutta,  India j 

Bombay,  Deccan ' 

Manila,  Philippine  Islauds 

Bangkok,  Siam 

Aden,  Yemen 

Trivandrum,  Deccan 

Kandy,  Ceylon 

Singapore 

Amboyna,  Molucca  Islands 

Batavia 

POLYNESIA   AND   AUSTRALIA. 

Honolulu,  Sandwich  Islands 

Raiatea,  Society  Islands 

Freemantle,  West  Australia 

Sydney,  New  South  Wales. 

Adelaide,  South  AusUHia 

Auckland,  New  Zealand, 

Wellington,  New  Zealand 

NORTH  AMERICA. 

Upernavik,  Greenland 

Fort  Simpson,  British  N.  America. 

Assiniboine,  Manitoba 

St.  Johns,  Newfoundland 

Montreal,  Pr.  Quebec 

Windsor,  Nova  Scotia 

St.  George,  Bermudas 

Matamoras,  Mexico 

Havana,  Cuba 

Mexico,  Mexico 

Vera  Cruz,  Mexico 

St.  Thomas,  West  Indies 

Balize,  British  Honduras 

Guatemala,  Central  America 

SOUTH  AMERICA. 

Maracaibo,  Venezuela 

Georgetown,  British  Guiana 

Bogota,  United  States  of  Columbia 

Quito,  Ecuador 

Para,  Brazil 

Lima,  Peru 

Rio  Janeiro,  Brazil 

Asuncion,  Paraguay 

Valparaiso,  Chili 

Montevideo,  Uruguay 

Falkland  Islands 


POSITION  OF   STATIONS. 


Latitude. 
(South  -) 


70  4(V 
64  33 

64  8 

60  24 
59  67 

59  55 
56  60 
55  58 

65  45 
63  6 
52  21 
62  30 
62  13 

61  30 

60  51 
48  80 
48  12 
46  25 
46  21 
45  45 
45  28 
44  51 
44  60 
43  47 
41  7 
40  25 
38  43 
38  11 
87  58 


36  47 

32  38 

30  2 

13  10 

6  24 

4  44 

-  6  28 

-15  55 

-29  40 

-33  50 


70  55 

62  2 
69  21 
58  2 

63  20 
53 

62  17 
41  41 
39  54 
33  21 
32  45 
81  47 
23  8 
22  38 
18  56 
14  36 
13  40 
12  46 

8  31 

7  17 

1  17 

-3  41 

-69 


21  16 
-16  40 
-32  16 
-33  40 
-34  35 
-86  60 
-41  16 


72  48 
61  61 
50 

47  37 
45  60 
44  69 
32  23 
26  62 
23  9 
19  30 
19  12 
18  21 
17  29 
14  40 


10  43 
6  49 
4  36 
-0  14 
-  1  28 
-12  3 
-22  24 
-25  16 
-33  2 
-34  54 
-62 


Long, 
from 
Green- 
wich 
(West  -.) 


23  46' 
40  34 
-21  55 

5  18 
30  18 

10  43 
60  34 

8  11 
37  34 

8  49 

6  15 
13  3 
21  1 

-  6 
4  22 
2  20 

16  22 
30  44 
48  5 
4  49 

9  21 

-  34 
20  26 

11  15 
28  59 

-3  41 

-9  8 
15  34 
23  50 


3  6 

-16  56 

31  15 

14  30 

10 

81  40 

39  30 

-  5  43 

31 

18  29 


138  24 
129  45 
143  11 
88  16 

103  27 
158  42 

104  11 
44  60 

116  26 

44  22 
129  52 

35  14 
113  16 

88  20 

72  64 
129 

10  1 

45  15 
77 

80  49 
103  50 
128  15 
106  63 


-157  69 

-160 
116  30 
151 

138  45 
174  61 
174  47 


-55  40 
-120  25 
-97  8 
-52  43 
-77  52 
-64  7 
-64  50 
-97  27 
-82  13 
-99  1 
-96  9 
-64  56 
-88  73 
-90  28 


-71  62 
-58  12 
-74  14 
-78  40 
-48  29 
-77  8 
-43  16 
-57  41 
-76  24 
-56  13 
-61 


Alt.  in 

Eng.  feet 

above 

ocean. 


852 
864 
490 
19 
19 
153 
825 

193 
121 

637 
167 


392 
42 
266 
234 
160 
1,327 
321 
222 


06 


1,760 


299 
13 

378 
300 

1,270 

1,487 


28 
2,610 


199 
1,790 


300 
.639 

266 
213 

65 

7,450 

4,960 


8,600 
9,543 


564 
262 


TEMPERATURE  IN  DEOREES  F'HR. 

January. 

July. 

Year. 

Below  ze- 

ro-.) 

22.5 

53.2 

35.5 

7 

61.5 

335 

30 

56.2 

39.4 

35 

60.4 

46.8 

15.6 

62.5 

38.8 

21.31 

61 

41.1 

2.3 

63.8 

33.2 

374 

58.5 

47.1 

11.9 

67.8 

40.4 

29.6 

64.6 

48.1 

40.4 

68.2 

48.4 

28.1 

66.2 

48.2 

21.5 

64.3 

44.3 

37.4 

64.1 

50.8 

36 

64.8 

50.3 

35.4 

65.6 

51.3 

28.9 

69.6 

60.2 

26.1 

71.5 

49.2 

19.9 

77.9 

49.2 

36.3 

706 

62.4 

33.3 

74.5 

64.6 

42.4 

69.1 

65.1 

33.3 

76.6 

54.2 

40.8 

76.3 

67 

40.4 

74.1 

57.6 

44.7 

76.3 

68 

48.6 

69.8 

59.5 

46.8 

76.4 

59.9 

45.6 

795 

62.4 

69.1 

80.4 

69.1 

63.5 

72.5 

67.6 

56.3 

85:6 

71.3 

75.7 

83.6 

83.3 

81.1 

77.1 

80.4 

89.4 

78.4 

83.1 

83.3 

77.1 

64 

58 

61.4 

76.2 

59 

67.8 

67.6 

64.4 

60.7 

-38.6 

52.6 

2.8 

-41.3 

63.2 

12.4 

-11.6 

54.6 

23.1 

-  2.9 

63.4 

83 

-4.4 

67.5 

32.3 

20.3 

58.1 

37 

-  6.5 

64.9 

30.7 

32.4 

75.6 

55 

25.8 

79.9 

54.6 

48.6 

93.2 

73.6 

42.3 

79.3 

61 

46.7 

76.4 

63.6 

52.5 

83 

69.9 

71.7 

84.2 

81.1 

73.3 

80.7 

79.8 

77.1 

80.3 

79.6 

76.7 

82 

81.1 

72.6 

83.4 

80.2 

78 

78 

79.2 

70.6 

72.6 

72.7 

78.4 

82.2 

80.7 

80.5 

77 

79-1 

78.7 

78 

78.8 

71.7 

78.9 

75.4 

78.7 

75.7 

78.4 

70.8 

67 

62.7 

71.7 

49.8 

61.3 

84.4 

54.2 

68.4 

67.9 

49 

58.6 

66.4 

48.7 

68.3 

-12.3 

385 

12 

-12.5 

61 

25.7 

-  2.9 

69.6 

35.3 

23.4 

66 

38.3 

16 

73.2 

44.6 

25.1 

63.5 

41.9 

65.7 

82.4 

72.7 

60.4 

84.2 

73.6 

71.4 

81.4 

77.1 

52.5 

65.3 

60.7 

71 

81.5 

77.7 

80.8 

82.7 

82.3 

76 

82 

79.5 

66 

68.9 

67.8 

81.3 

86.6 

84.7 

78.4 

79 

79.5 

57 

56.2 

57.7 

58.2 

59.1 

60.1 

80.1 

81.5 

80.6 

78.1 

68.6 

73.3 

79.6 

70.6 

75.2 

365 

65.1 

74.3 

66 

57.3 

60.6 

73 

51.8 

62.1 

56 

37.4 

47.2 

Note.  — The  altitudes  given  above  refer  to  the  position  of  the  instruments  used  in  observation. 

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